BRUSSELS, Belgium (AP) _ Analysts say prospects are good for cutting conventional arms in Europe because of the similarities in the initial proposals of NATO and Warsaw Pact nations.

''The starting positions are quite reasonable (and) give plenty of room for compromise,'' said Richard Fieldhouse, a research fellow at the Stockholm International Peace Research Institute in Sweden.

The 16 nations of the North Atlantic Treaty Organization and the seven of the Warsaw Pact began negotiations Thursday in Vienna on reducing conventional arms in the region.

''We are not really that far apart,'' chief U.S. negotiator Stephen Ledogar said after the opening session. Soviet negotiator Oleg Grinevsky said the gaps were not insurmountable.

''It looks like there's political will (and) interest to do the things required for an agreement,'' Fieldhouse said Friday. ''The question is: Can those things be maintained - are they real and are they permanent?''

Negotiators will be under enormous pressure to succeed. A 15-year effort to cut those weapons in Central Europe failed.

In their starting proposal, NATO negotiators called on the Warsaw Pact to cut tanks, artillery and armored troop carriers. NATO would make smaller cuts of 5 percent to 10 percent in those categories.

In its initial offer, the Warsaw Pact proposed a first-phase reduction ranging between 10 percent and 15 percent of the lowest level of arms held by either side.

The percentage cuts proposed by each side are not far apart, although the East wants the trims to include aircraft, which Western officials oppose.

NATO contends the Soviets and their allies have built up a huge superiority in conventional weapons in Europe. The alliance wants the East bloc to make much greater cuts in their forces to bring the two sides to equal strength.

Analysts said the Soviets appear ready to follow the West's call for greater East bloc reductions to reach parity in the weapons systems.

They noted Soviet President Mikhail Gorbachev's recent promises of reductions in his nation's troops and defense spending.

''You don't make unilateral cuts unless you recognize you have a lot and too many,'' said Fieldhouse. ''That's a big point in favor of progress.''

The West would like a total of 40,000 main battle tanks, 33,000 artillery pieces and 56,000 armored troop carriers in Europe. Each side would be allowed half the total.

U.S. officials estimated this would require the Warsaw Pact to get rid of 31,000 tanks and NATO, 2,551. For artillery, the cuts would amount to 26,900 for the East and 828 for the West.

The officials calculated the Warsaw Pact proposals, using a 10 percent reduction, would mean cuts of 31,849 Eastern tanks and 3,069 for NATO. The East's artillery would be slashed by 20,206 pieces and NATO's by 5,706. The East would give up 28,120 armored personnel carriers and the West 4,690.

Despite similarities in positions, the differences portend long, possibly acrimonious, debates.

Soviet Foreign Minister Eduard A. Shevardnadze has insisted the talks cover aircraft, an area in which the Soviets contend the West holds the edge.