Maryland depositors may be the biggest winners and shareholders in Maryland banks and savings and loan associations the biggest losers under the banking bills pending in the state legislature.

The legislation will permit big out-of-state banks to open facilities in Maryland while preventing most of them from merging with or buying Maryland institutions. Whether there are any measurable winners or losers caused by the controversial legislation depends mainly on how much big out-of-state bank companies like Citicorp covet Maryland banking business and how aggressively they are willing to pursue it, bankers and other analysts said.

The Maryland Senate on Thursday approved two banking bills already passed by the House -- although there are differences in the House and Senate versions that must be ironed out.

One bill would grant Citicorp -- which owns New York's Citibank, the nation's largest -- full banking powers in Maryland. The bill would permit other banks from outside the region the same rights as long as they agree, as Citicorp has, to create 1,000 jobs and open a $25 million facility in Maryland. There are minor differences between the House and Senate versions, but either version will make Citicorp a full-service bank in about 15 months, with no meaningful restrictions on its ability to set up branches.

The other bill would establish regional banking designed to permit bank companies in 12 other Southeastern states and the District of Columbia to buy or merge with one another. In the House version, banks from states outside the compact would be permitted to buy Maryland banks after four years. The Senate version has no such "nationwide" provision, but does add Pennsylvania to the compact.

Regional banking bills are being considered or have been approved in other Southeastern states. Virginia approved one last month; the District is holding hearings.

The full impact of the so-called Citicorp bill depends on the still-undefined intentions of the money center banks. But one thing is clear: The big banks are mainly interested in the Baltimore-Washington corridor. Most certainly, analysts said, the fears of rural Maryland banks that they will be overwhelmed by rich money center banks are virtually groundless.

"I just can't believe that Citibank is interested in the Eastern Shore," said one top executive of a major local bank. "But I can see them interested in Baltimore, Bethesda or Rockville."

Although interstate banking is controversial, in reality interstate banking has existed for years both for business loans and for large deposits. Most of the major bank companies also own large finance companies that compete for consumer and business loans and have major credit card operations that are nationwide in scope.

What banks have been prevented from doing is setting up facilities in other states that can collect deposits from small and medium-sized retail and business customers and offer them regular bank loans, which generally carry lower interest than finance company loans.

If a Citibank/Maryland or Chase Manhattan/Maryland is interested in developing a large consumer business, the best way to get business is to offer higher rates on deposits or lower rates on loans than current Maryland banks or savings and loans offer, bank executives said.

"There won't be any new banking business, so if Citibank wants it it will have to attract it from another institution," said the president of a big Maryland bank. "At first, that business might come from savings and loan associations that now offer higher rates than commercial banks." Eventually, the banker said, banks would probably see some of their business go to newly established out-of-state banks too.

By permitting big out-of-state banks to set up their own facilities and preventing them from buying Maryland banks -- whether for four years or forever -- legislators may have reduced the value of the franchise of current Maryland banks.

"If Citibank, Chase Manhattan Bank or Chemical Bank have spent the money to establish banks and branches, by 1989 they're probably going to be less willing to pay a high price for a Maryland bank," said the chief executive of one local bank.

In other words, one way into the Maryland banking market is to buy a Maryland bank. The other way is to set up a new bank. "Anytime you reduce the number of potential purchasers of my bank, you probably reduce the value of the bank to my shareholders," said the chief executive of a major local bank.

Regional bank compacts -- which got their start a few years ago in New England -- assume Congress will eliminate the barriers to interstate banking in the not-too-distant future. By lowering barriers to a restricted number of states, the compacts assume that the regional banks in their confines will consolidate before they have to face competition from industry giants based in cities such as New York, Chicago and San Francisco.

Maryland's wrinkle is to allow any out-of-state bank willing to create jobs and make investments in Maryland the right to establish their own banks.. These banks would have to operate as limited-purpose banks for two years before starting full competition.

It's been called the Citicorp bill for good reason. Gov. Harry Hughes, to the chagrin of the state's bankers, worked out a deal with Citicorp, which is the only out-of-state bank already operating a limited service facility in the state, to establish a full-service bank with branch rights. In return, Citicorp agreed to set up a credit-card processing plant in Hagerstown and create 1,000 jobs within a few years.

Citicorp already is nine months along toward the two years of limited-service banking it must engage in before getting full-service privileges. But other giant banks are interested in Maryland too. Chase Manhattan Corp. has applied for a limited-service charter and Chemical New York Corp. said it expects to file an application next week.

Whether Chase and Chemical will make investment and job-creating commitments to the state in return for the right to set up their own Maryland banks is far from sure. "We want to keep our options open," said an official at one of the two banks. He asked that neither he nor his bank be identified.

The Maryland Bankers Association has waged a bitter, unsuccessful struggle to torpedo the Citicorp bill. Most of its members assume they would be hit hard by aggressive competition from money center banks.

But if Citicorp's behavior in California, Florida and Illinois is indicative, Citibank/Maryland will be competitive but not overly aggressive. If Citicorp's record in upstate New York -- where it set up a bank several years ago -- is repeated in Maryland, Maryland banks again can sleep easy. Citibank has struggled, with but limited success, to penetrate upstate New York.