The meanings are very similar, but "infamous" is a bit more intense, and usually describes someone who is very widely known ("famous") for their bad deeds. Major public figures like politicians can be "infamous," but you normally wouldn't describe a coworker as "infamous" (unless you're intentionally exaggerating how important his evil deeds are). "Notorious" doesn't necessarily mean that the person is famous, and the bad things they do might not be very serious (though they can be). Basically, "notorious" means that their bad deeds are well-known within some area or group of people. We usually use the word "notorious" along with a description of what bad things the person is known for doing. For example, we can say "he's a notorious liar" or "he's notorious for cheating on exams." "She's notorious for always showing up late" means that everyone (e.g. all her friends, everyone in the company, etc.) knows that she's always late. The word can also refer to serious crimes, but it doesn't have to. "Infamous," on the other hand, is much more likely to refer to something serious. You wouldn't say that someone was "infamous" for being late to meetings (except maybe as a joke).

There is nearly no difference really. From my perspective, "notorious" can *sometimes* be used in a way that doesn't imply as much negativity (for example: His mom was notorious for wearing that same hat all the time"). But really, they mean the same thing and can be interchangeable.

There is pretty much no difference because they mean the same thing.