The two titans of business lists, Forbes and Fortune, agree that General Motors Corp. was the biggest company in the nation last year.

But from there, the two agree on little else.Forbes says General Electric Co. is the winner in its "Forbes Super 50" - its rankings of the 50 most powerful corporations - while Fortune says the oil companies stole the show with the biggest gain in profits.

GM, which took in more than $120 billion last year, topped sales rankings of 500 companies released by both publications Monday.

It edged out Exxon Corp., with revenues of $106 billion. Rounding out the top four at both magazines were Ford Motor Co., with sales of $98 billion, and International Business Machines Corp., at $69 billion.

The two magazines differ in their lists, not only on the actual sales figures - they disagree about revenues at both GM and Exxon - but also who should be on the lists.

While Fortune lists only industrial companies, Forbes also includes service companies.

"It's shortsighted to exclude half of the economy, in effect," said Ray Healey, director of editorial information at Forbes. He called Fortune's list "one-dimensional."

Healey asserted that the "Forbes Super 50" is the "most comprehensive ranking of companies." The magazine bases its list on combined rankings of sales, profits, assets and market value. Fortune uses only sales.

GE topped all companies among the "Super 50," with Exxon and IBM following. GM, which also was at the top of the 50 in 1989, stalled last year and didn't even make a showing because it lost $2 billion.

Fortune officials were not impressed with the Forbes list.

"Our list is the gold standard," said spokeswoman Emma Dockendorff, pointing out that this is the 36th year of the Fortune 500. "They're trying to jump on our coattails."

"The lists are completely different. And we have no idea of how Forbes comes up with its numbers," she said.

Forbes insists its figures are correct, despite the discrepancy in sales for some companies. "In this case, we are right," says Don Popp, the magazine's statistics editor.

Oil giant Exxon jumped from No. 3 to No. 2 in sales on both lists, beating out Ford, while IBM retained its position as No. 4.

Oil companies moved up the list, benefiting from the high oil prices caused by the Persian Gulf crisis.

Mobil Corp., Texaco Inc. and Chevron Corp. all gained. Fortune said the petroleum refining industry had the biggest increase in profits among industry groups, up 32.6 percent.

The biggest losers, also according to Fortune, were makers of transportation equipment, which suffered as higher oil prices hammered airline companies.

Fortune said the sector's profits fell 96 percent on average, although aircraft maker Boeing Co. saw sales grow. It rose to No. 13 from 15 on the Fortune list and to 18 from 21 in the Forbes ranking.

Among the big losers: Chrysler Corp., where sales slid 12 percent or 15 percent last year - depending on which list you consult. Chrysler slipped to 11th from eighth on the Fortune list and to 16th from 12th on Forbes' list.