They deregulated airlines last year, they are working on trucking and new members of Congress are wrapped up in a real Pier Six brawl on the whopper of them all -- banking deregulation.

It is a House-Senate fight that affects almost everyone. Airlines and trucks can be avoided, but there is almost no way to elude the touch of lending institutions -- banks, savings and loans, credit unions, mutual savings banks.

The fight is about a pact that has compartmentalized the lending industry over the years, and has protected savings and loans from banks. Mainly, the banks have not been allowed to pay as much interest on savings accounts as the savings and loans. The object was to give the S&Ls -- the main sources of mortgage money in this country -- a partial advantage in attracting funds.

In return, the S&Ls have not been allowed to compete with banks for certain other kinds of business, such as checking accounts.

Now, however, some people think the two main groups with a stake in this system, home buyers and small savers, would be better off without all the protective rules.

Cheered on by the Carter administration, which calls reform essential, the Senate this month passed a major "depository institutions" deregulation bill designed to put an entirely new face on the thrift industry.

There would be no more limits on interest payments on savings accounts. All institutions could offer checking accounts and pay interest on them. Savings and loans could deal in credit cards and consumer loans. Small savers would be eligible for the certificates of deposit now available only to big savers. State usury limits on many loans would be abolished. Other features would make it a monumental reform bill.

A much more modest vesion has gone through the House, setting the scene for a conference that must work out variations between the sharply contrasting bills. Conferees are not expected to meet until next month, adding to the pressure as the congressional session ends.

As with any legislation involving such vast amounts of money and such politically important people as bankers and other lenders, Congress is under immense pressure to come up with answers, but this fight involves far more than the usualy industry vs. Consumer squaring-off.

It has generated a torrent of lobbying on Capitol Hill, with more to come soon, from the biggest banks to the smallest savers. It has pitted big bank against small bank, divided the savings and loans, excited the credit unions and split consumer and labor groups.

Big banks, represented by the American Bankers Association, are thrilled with the Senate bill, envsioning more business but clothing it in a defense of the saver's need to get higher interest rates.

Smaller, mostly rural banks, represented by the Independent Bankers Association of America, oppose the Senate bill. They fear big-bank takeovers and lose of business to competitors.

The U.S. League of Savings Associations, more than 4,000, mostly small savings-and-loan outfits, is opposed strongly to elimination of the interest-rate advantage now held over banks. Many members think the Senate bill would force them to become more like full-service banks, rather than mortgage servicers. Construction unions, worried about reduced home-mortgage money, agree with the league.

But the National Savings and Loan League, composed of generally less conservative and larger S&Ls in urban areas, likes the Senate bill, because it offers them new business possibilities in checking and electronic accounts.

Also happy with the Senate bill is the Credit Union National Association Inc., whose members are so eager to get into checking accounts that they bilized Congress this year with an estimated 150,000 letters demanding actin.

Add to that mix consumer groups, led by senior-citizen organizations, which generally support the Senate bill, and the AFL-CIO, which doesn't like it, and you are talking about some heavy pressure.

With so many disparate interests tugging at their sleeves, most members of Congress say they wish the fight would go away. And it has left House and Senate banking leaders staring at each other in a sort of legislative chicken game in which the first blink means big, big bucks.

Who will get them, and how, or whether, are the issues.

Staring from the House side are Reps. Hency S. Reuss (D-Wis.), Banking Committee chairman, and Fernand J. St. Germain (D-R.I.), a key subcommittee chairman, who say economic conditions are too precarious to permit large-scale tinkering.

Staring from the Senate side is William Proxmire (D-Wish.), the Banking Committee chairman, who says reform will encourage savings, stem inflation and give small savers a fairer return on their deposits.

"It is war," said a senior official of the ABA, "because bankers see this Senate package as the best that's ever come along to wipe out their biggest competitive stumbling blocks."

The main block is seen as Regulation Q, which holds down all interest rates on savings accounts but permits S&Ls to pay a slightly higher rate of interest (5.5 percent) than banks (5.25). Regulation Q, opposed by the Senate but supported by the House, ir rooted in the belief that S&Ls need help to attract money so they can maintain their key role as financiers of the bulk of the country's home mortgages.

But, many experts point out, in a time of high interest rates, such as today, that system doesn't work anyway. Even relatively small investors can find other places to put their money, and get higher interest rates than passbook accounts.

The major S&L trade group, the U.S. League, is bitterly opposed to ending Regulation Q, fearing erosion of its favored position as a principal source of mortgage money. Aligned with the league is the AFL-CIO, whose building trades unions don't want theorists playing games with an already precarious home-building industry.

An additional voice calling for an end to Regulation Q is President Carter, who has said it is "particularly unconscionable" for the government to tolerate unrealistic interest limits that prevent small savers from getting the same kind of return as large investors.

"The real point," said ABA's Ed Smith, "is that this is a consumer issue. We are persuaded that it will be wond by consumers. If people care about losting 6 percent on their life savings because of current regulations, they ought to speak up."

To help Congress get the message that the larger banks want an end to Regulation Q, the ABA plans to bring 400 bankers here in two weeks to work a full court press on Capitol Hill.

On top of that, ABA state affiliates are promoting letter campaigns, and the ABA has placed full-page ads in Milwaukee, Boston and Chicago newspapers to pressure three key House conferees -- Reuss, St. Germain and Frank Annunzio (D-Ill.).

"It is almost the classic situation," said Everett Engstrom, an aide to Sen. Robert Morgan (D-N.C.), who headed an unsuccessful effort to dilute some of the Senate's sweeping reforms.

"The bulk of the members of Congress don't focus on these issues. And if you don't have a consensus of the House and Senate Banking committees, you then have open warfare among the financial institutions. It becomes more of a political argument than economics."

A complicating factor in all this is the calendar. Congress has, by U.S.

Court of Appeals decree, until Jan. 1 if it wants to rescue millions of consumers whose money is now in experimental savings programs the court ruled illegal.

Unless Congress rules otherwise, experimental check accounts in 1,000 credit unions will end. So will specail automatic transfer accounts worth $6 billion in some commercial banks. So will 700,000 S&L customers' accounts in experimental remote-service units (money machines).

The House-passed legislation is aimed at resolving those problems by authorizing and extending the programs. The Senate, under prodding by Proxmire and Alan Cranston (D-Calif), followed suit, then added enough more deregulation to ear its bill a "Christmas-tree" label.

At its simplest, reregulation means removing regulations from an industry and allowing all forces to compete equally. The best and most efficient (the theory goes) survive, no one is propped up by special treatment and (the theory continues) the consumer wins.

The Senate measure would wipe out most of the regulations that make banks, mutual savings banks, savings-and-loans and credit unions so different, each with its own appeal and specialized kind of service.

Proxmire couldn't help but notice the irony. The appeals court decision came in cases brought by the different trade groups, challenging different regulations that aided rivals.

"It's the darnedest thing," he said the other day. "All these people moan and groan that they don't want federal regulations. But they don't want to give up the advantages that the regulations give them. I made a speech like that to some truckers and they reacted like I was a skunk at their picnic.