The New York attorney general’s decision to investigate Exxon Mobil over whether the company lied to the public and investors about the risks of climate change has raised questions about possible similarities to the Justice Department’s successful suit against the tobacco industry in 1997.

The new case has reprised the famous question from Watergate — What did they know, and when did they know it? — which also was an important element of that tobacco lawsuit.

But there are important differences in the two cases, legal experts note. The tobacco industry largely hid its evidence of the addictiveness and harm of tobacco, while Exxon published peer-reviewed climate change research even as it supported groups that criticized policies to deal with climate change and raised doubts on the underlying science.

That basic difference presents a hurdle — but by no means an insurmountable one — for efforts to prosecute the company, the legal experts said.