HOUSTON, JULY 11 -- While the leaders of the world's seven big industrialized democracies talked about aid, arms and the atmosphere here this week, the participants in that other "summit" -- the leaders' spouses -- studiously sidestepped the issues.

"We were very carefully avoiding that," said Barbara Bush in an interview today of the unspoken rules they abided by. "You don't want to divulge the differences. You want to divulge the samenesses, so we didn't discuss any of the issues on the table. To tell you the truth, I don't think we had that many differences. There was no tension I could feel at all."

The First Lady's behind-the-scenes glimpse of life at the top portrayed a group of compatible people who laughed, saw and learned a lot in the short time she had to show them her Texas.

"I think they were overwhelmed by the American and Texas hospitality," Mrs. Bush said. "Everybody mentioned how great it was to go to a private home, how they couldn't believe our friends would open up their homes. But having said that," Mrs. Bush said, laughing, "we do have a little trouble competing with Versailles and places like that."

One of the toughest decisions, she said, was whom to invite to Betty Liedtke's dinner here Monday night and Joci Straus's lunch in San Antonio on Tuesday.

"I very carefully decided we could have nobody come politically -- I mean Democrats or Republicans. Just the {hostesses'} children and three of my very close friends," she said.

She went on to add that Susan Baker, wife of the secretary of state, "gets no credit or blame -- the blame, I'm trying to save her from."

Working together, Mrs. Bush, Susan Baker and Kitty Brady, wife of the secretary of the treasury, sent personal handwritten notes to each of their counterparts this spring expressing the hope that they would be coming to Houston with their husbands. They followed up the acceptances with queries about what they'd like to do once they got here.

"We just made a decision we three would do it as a team," Mrs. Bush said, adding, "How lucky I am to have two women I've known and adored for years, so it made it so much easier."

She said the wives of the foreign and finance ministers, usually overlooked in summit arrangements, were "thrilled" to be included. And, in fact, of all the wives, she probably had known Barbara Genscher, wife of West Germany's foreign minister, the longest.

She called Italy's Livia Andreotti "absolutely one of the coziest, warmest people," but also a woman who isn't "self-assertive." Andreotti, like Japan's Sachiyo Kaifu, "who had the best time in the world and gave everybody the best time," had to be encouraged. "You have to pull them forward because they wait back," Mrs. Bush said.

Canada's Mila Mulroney, she said, was "everybody in the world's favorite" and had been enormously helpful because she is fluent in French: "I told her I was going to pay her for interpreting."

France's Danielle Mitterrand was "fascinating. She has all sorts of interesting causes, she's very gracious, and when she smiles it's really worth it," Mrs. Bush said. "I like them all. It was a wonderful opportunity for me to get to know them better. It gives you an extra dimension."

Would her highly organized spousal summit set a standard others might find difficult to maintain? She countered with a question.

"You think Denis {Thatcher} is going to have fun next year? I didn't ask Margaret. I gave her a big kiss goodbye and I thought, 'Darn -- I wish I'd said I hope Denis works something up for us.' "

Britain will host next year's economic summit.

She said Denis Thatcher really hadn't planned to come at all this week and changed his mind only at the last moment. He left town after Monday night's dinner, given by Betty Liedtke, but Mrs. Bush said, "He had a very good time. You know he's a wonderful, supportive man and he has a very full career of his own."

At the official arrival ceremony here Monday, Prime Minister Thatcher and her husband were greeted by President and Mrs. Bush.

"I said, 'Don't kiss my hand, Denis, because I'm not going to kiss yours back. You know I got in plenty of trouble with that and I'm not going to do it again,' " Mrs. Bush said, adding, "Maybe."

Denis Thatcher, however, ignored her entreaties, much to the delight of photographers.

Of the Bushes' various activities through the week, Mrs. Bush said she thought the entertainment was "fabulous" and "not at all a little heavy on country music. The president loves it and it was his party. But I thought the balance was very good. Of course you have country music at a rodeo and we only had one country music {act}" at the windup dinner Tuesday night.

She had been "absolutely thrilled with the ping-pong man {juggler Michael Davis}. I loved it because President Mitterrand was dying of laughter, and so was Danielle."

Of Bush's missing toast at the dinner, she said, "if the president's speech was left at home, he did not complain about it, so it was no big deal to him. I didn't miss it. I think the less speeches, the better."

If there were any snafus or embarrassingly funny moments during the summit, Mrs. Bush would be the last to tell. "We laughed a lot, but thank God nothing funny happened," she said.

Then she remembered riding with Susan Baker and Kitty Brady after Monday's arrival ceremony and seeing 20 elephants crossing an enormous eight-lane highway, closing yet another road in the already traffic-burdened city. That reminded her of people with signs she saw on today's parade route. One of them read, "So long, Sununu." "I wasn't quite sure what that meant. I can't wait to ask John," she said.

Today's schedule for the First Ladies began this morning with a visit to the Texas Medical Center, a huge complex of hospitals, clinics, and medical and nursing schools with a work force of 52,000.

"I couldn't think -- nor could Susan {Baker} -- of any one place that better exemplifies what Houston and Texas are all about: love and caring and consistent striving for excellence," she said at the welcoming ceremony.

After that she and the spouses broke up for individual tours. Danielle Mitterrand, for instance, went to see the Texas Heart Institute while Mila Mulroney opted for Texas Children's Hospital. Some of the women returned with their husbands this afternoon, after the summit broke up, Mrs. Bush said.

But in the morning, instead of having 19 people on the same tour -- "they only pay attention to the top ones and nobody ever listens," Mrs. Bush said -- the women were able to see facilities of particular interest to them.

She chose the M.D. Anderson Hospital and visited outpatient centers for both adults and children under treatment for cancer.

"One adorable boy about 18 or 19 had tiny fuzz on his head. He said, 'If I had known you were coming I'd have moussed up my hair,' " Mrs. Bush said.

What impressed her was how so many of those under treatment are able to go back to work after a session of a couple of hours. The practical side of it is that "it cuts down on costs amazingly -- plus the psychological benefits."

Visiting youngsters undergoing treatment reminded her of her own daughter, Robin, who died of leukemia at the age of 3. "I'm very philosophical about that and how far they've come. What saints those doctors and nurses are."

Many of the children she saw wore caps on their heads to cover hair loss from chemotherapy. One child wore a mask over her mouth and had an intravenous tube in her wrist.

Seven-year-old Patrick Chapman of Houston was celebrating his birthday, and the First Lady sought him out to say hello. Later, checking his teeth and noticing a lone incisor surrounded by gaps, she remarked, "It's going to have a friend, isn't it? They're going to call you 'Fang.' "

Talking to another group, she asked their ages, then volunteered that she's 65. "It's not all bad," she assured them.

She specifically asked to meet a youngster from the Soviet Union, Denis Loktev, 15, under treatment here for nearly five months.

"We had a wonderful visit from your president," she told him. "Did you feel sort of proud of your president?"

His answer, a vigorous shake of the head, wasn't what she expected. "Yes you did, sure you did," she insisted.

She said her daughter, Doro, was born at Hermann Hospital in the complex, and she still remembered that the room number was 364.

Later, she confessed that she had had some doubts. "I was thinking,'Oh, gosh, don't tell me I'm in the wrong hospital.' "