The differences in budget-cutting strategy between the Reagan administration and Congress aren't clear yet, but here's one example of a difference in approach: while the Reagan budget-snippers are huddled in their offices with blue pencils and pocket calculators, the congressional budget-writers are headed for Europe to see how it's done there. c

Wilson Morris, a spokesman for the House Budget Committee, said the travelers are mainly interested in British Prime Minister Margaret Thatcher's conservative policies, because "those are the polices that we apparently are about to follow."

So 10 members of the 29-member committee, along with nine congressional aides and two private consultants, will jet off for London today, with side trips to Belgium and Italy, looking for information that Morris said is not available in Washington.

They'll stop in Rome for an audience with Pope John Paul II, whose position on supply-side economics is not known, and they'll all be back in time to hear President Reagan outline his economic program Feb. 18.

Scheduled to make the trip are Reps. James R. Jones (R-Okla.), the committee chairman; Jim Mattox (D-Tex.); Richard A. Gephardt (D-Mo.); Les Aspin (D-Wis.); Bill Hefner (D-N.C.); Beryl Anthony (D-Ark.); Delbert L. Latta (R-Ohio); Bill Frenzel (R-Minn.); Ed Bethune (R-Ark.) and Paul S. Tribble Jr. (R-Va.).

Meanwhile, a coalition of environmental groups eager to help the presidential trim back federal spending suggested slicing funds out of federal water projects and stopping further funding of the Tennessee-Tombigbee Waterway in Alabama and Mississippi.

Both projects, incidentally, were opposed by members of the coalition, which includes the Sierra Club and the National Wildlife Federation.