GENEVA (AP) _ On the eve of their own mini-summit, Raisa Gorbachev and Nancy Reagan attended separate welcoming receptions with Switzerland's first lady on Monday and sparked a comparison of their fur fashions.

When the stylish Mrs. Gorbachev arrived in Geneva on Monday morning with her husband, Soviet leader Mikhail Gorbachev, she descended from the Aeroflot plane in an eye-catching, tailored grey coat. It was adorned with a fur collar and she wore a matching fur hat, which appeared to be either grey mink or silver fox.

Several hours later, Mrs. Reagan appeared in an elegant dark mink coat and matching hat at the official Swiss welcome for her husband, President Reagan.

When Mrs. Gorbachev first emerged on the international scene in London last December, she grabbed headlines with her attractive clothes and open style, a sharp contrast with the plain looks and drab garb of her predecessors.

In contrast, Mrs. Reagan, a former actress, was criticized during her husband's first term for paying too much attention to her clothes and high society friends.

On Tuesday, the U.S. and Soviet first ladies will meet for the first time in 10 years over tea, and probably coffee as well. The backdrop will be the countryside mansion, Maison de Saussure, where the Reagans are staying.

It is the first such tea between superpower wives since Pat Nixon visited with Viktoria Petrovna Brezhnev at the Kremlin in June 1974.

Mrs. Gorbachev will host a return tea on Wednesday for Mrs. Reagan at the Soviet mission.

A Soviet delegate, speaking on condition of anonymity, said Mrs. Gorbachev ''doesn't want to show off. ... She takes this visit very seriously.''

Elaine Crispen, press secretary to Mrs. Reagan, said the U.S. first lady is not interested in competing with her Soviet counterpart.

''She's not going in with any talking points,'' Mrs. Crispen said. ''It's just a matter of getting acquainted, just a good chance to exchange views. ... She'll get into people, not policies.''

Mrs. Reagan and Mrs. Gorbachev were served light refreshments by Swiss first lady Ursula Furgler after separate formal welcoming ceremonies for their husbands at Le Reposoir, an 18th century villa overlooking Lake Geneva.

Mrs. Reagan wore a dress in her favorite color of red, a gold necklace, and kept her mink hat on. Mrs. Gorachev wore a mauve silk blouse with a matching tie, black velvet skirt, gold earrings and took her hat off.

Before their 45-minute tea on Tuesday, both first ladies have lined up rather serious schedules, with no time set aside for frivolous activities.

In Paris last month, Mrs. Gorbachev visited the shops of Pierre Cardin and Yves St. Laurent, but the Soviet official said she will ''absolutely not'' visit any fashion houses in Geneva.

According to Swiss officials, Mrs. Gorbachev will visit City Hall, the watch museum, the offices of the United Nations and the library where Vladimir Lenin studied during his years in exile in Geneva.

Mrs. Reagan, who has campaigned internationally against drug abuse, will hold a talk session at a drug treatment center and visit a medieval Swiss village with American and Swiss youngsters.

Mrs. Reagan invited Mrs. Gorbachev to tea months ago, saying she in her invitation that was sure they both ''want to do all we can to improve understanding between the people in our two countries.''

Yet the amount of attention being focused on the meeting has been intense, Mrs. Crispens says. The White House has received dozens of questions on such minor matters as the kind of tea Mrs. Reagan will serve.

But on the eve of the event, Mrs. Crispen said the U.S first lady still had not decided what type of snacks will be offered Mrs. Gorbachev, or whether U.S., English or some other kind of tea will be served.