Tucked away in the fine print of the federal government's half-trillion-dollar budget are scores of policy decisions, large and small, some announced previously but many others not.

The federal government will sharply increase its policing of civil rights violations, but it will cut back its fight against certain crimes, such as bank robbery. It will try to cut the flow or illegal aliens from Mexico, but increase the influx of refugees from Asia and the Soviet Union. It will reduce spending for a new bomber, but start putting money into a new spy plane. It will try to discourage consumption of some commodities, such as tobacco, but work to increase use of others, such as helium.

One of the most striking changes from last year's budget is in the area of civil rights enforcement. The Carter budget anticipates a considerably stronger anti-discrimination effort, including a "significant increase" in school desegregation cases in major metropolitan areas.

The Equal Employment Opportunity Commission, the chief federal police force against job discrimination, would receive $104.5 million for the year, a 35 per cent increase over its current budget.

The commission will use the new money in two ways, according to the budget presentation.It will try to reduce its enormous backlog of unresolved cases (a "work-flow analysis" calls for the agency to settle 116,600 complaints in 1979, which for the first time would be more than the number it expects to be filed, 104,300.

And it also plans to concentrate more on "patterns and practices" than on individual discrimination cases.

An even bigger increase in civil rights enforcement funds is being sought by the Department of Health, Education and Welfare. Its Office for Civil Rights, which pursues alleged discrimination in virtually every local and state school, hospital, health, welfare, social service and education agency, will more than double its present operation. That means a $38 million increase for 1979 - to $72 million - and the hiring of almost 900 more full-time personnel.

The FBI, in contrast, will suffer a small loss of personnel under the Carter budget. The agency will lose 500 positions, bringing its work force just below 20,000. According to the budget, the bureau will adjust to the decrease by devoting less manpower to bank robberies (which will be left more often to local police). The FBI will increase its police work against organized crime, the budget indicated.

Despite the decrease in FBI people, the budget calls for the purchase of 1,374 new FBI cars - almost three times the number the bureau bought last year. The vehicles, the budget decrees, will be "for replacement only."

Another law enforcement agency receiving a major increase from the new budget is the Immigration and Naturalization Service, which will get 903 new border patrol guards - a 9 per cent increase - to try to dam the flood of illegal aliens crossing the border from Mexico.

The budget reflects shifting concerns towards refugees from various parts of the world.

The Cuban assistance program, which dates back to 1959, is being phased down to $51 million and is scheduled to end in 1983.

A new Southeast Asian refugee program, to follow on with one enacted in 1975, will provide $94 million in fiscal 1979. It would fund federal programs that support refugees from Vietnam, Cambodia and Laos.

The United States will also take over, through the State Department, a $20 million program to support resettlement of Soviet and other East European refugees in this country.

This year the funds were provided for placing the refugees in Israel.

The budget reflects President Carter's decision last year against full production of the B-1 bomber; funding for new prototype models has been eliminated. But it does provide "advance procurement funds" for another new plane, the TR-1, which is designed to be a fast, high altitude spy plane along the lines of U-2.

The federal government's spanking new war on cigarettes shows up in the budget as a $30 million line item in the HEW appropriation to fund anti-smoking advertisements and educational materials and research into effective ways to help smokers stop.

That expenditure will seek to counter the effects of the government's tobacco subsidy program, which will cost $32.9 million in fiscal year 1979. The subsidy expenditure represents a sharp drop from present spending, $75.5 million. The government expects the market price of tobacco to increase next year, reducing the subsidies.

While it seeks to cut tobacco consumption, the government will try to encourage use of helium. Because of long-standing contractual commitments, the federal government each year acquires for more helium than it can use or sell.

In fiscal 1979, for example, the government expects to buy $57 million more worth of helium that it can sell, the budget shows. If that prediction holds up, the government will have more than $650 million tied up in helium supplies by the end of the fiscal year.

Various agencies are chipping in to help find work for the Glomar Explorer, the $350 million ship built for the Central Intelligence Agency to lift a sunken Soviet submarine from the ocean floor four years ago.

Two years ago, the Glomar was put in mothballs.

Now, the National Science Foundation wants funds to use it to drill exploratory holes in the ocean floor to recover sediments buried by nature's upheavals longer than one billion years ago.

The Department of Energy also has plans to use the submersible mining barge, built as part of the Glomar operation, that once was to pick up the sunken sub. DOE's idea is to convert it to serve as an ocean thermal energy test facility.