Aggravating and Extenuating factors / U.S. Law / Re Kansas v. Marsh

Can someone please explain/define aggravating factors and extenuating factors in legal terms (actually, translate the legal terms to layman’s terms).
Reading about Kansas v. Marsh my confusion about these terms is getting in the way of my understanding of the case.

Some sources I’ve read are using the term “mitigating” where other sources are using “extenuating”.

bump- of the "awww, c’mon variety

Awww, c’mon, folks! This is a simple “define this two legal terms” question.
41 views and no help? I know for a fact that there are people here for whom this question has got to be super easy.

What say?