CUOMO AND RIVALS IN LOW-KEY DEBATE
After months of long-distance campaigning in which they impugned each other's character and ethics, Governor Cuomo and Westchester County Executive Andrew P. O'Rourke took it all back yesterday. The Governor and Mr. O'Rourke, the Republican candidate for governor, appeared with District Attorney Denis E. Dillon of Nassau County, the Right to Life Party candidate, in their only debate of the campaign, a 90-minute session at The New York Times. The debate produced disagreement on some issues but less heat than their repeated arguments over whether and how to debate - an issue that has dominated the campaign. The exchange was a snapshot of the campaign as a whole - Mr. Cuomo not making commitments, Mr. O'Rourke failing to engage him - that went a long way toward explaining why Mr. Cuomo holds a lead of 50 percentage points in the polls. [ News analysis, page B5. ] Aides of both Mr. Cuomo and Mr. O'Rourke said they had urged their candidates to tone down the remarks so that Mr. Cuomo, a skilled debater, would not come across as the heavy or so that Mr. O'Rourke would not appear undignified. ''Everybody was on their best behavior,'' said the O'Rourke campaign communications director, Richard Behn.

