Since you've drawn the comparison, it's worth pointing out that a notable difference is that Nancy Pelosi was not (nor was running to be) POTUS and could not have unilaterally gotten the US into a war in the middle east.

Amusingly enough, she was Speaker of the House, which means at one point she had more legitimate power to enact war than Trump ever has. The Congress must first vote to declare war, and only then can the President sign and execute it. Legitimately.