Somebody really should come up with better names. I know for a fact I knew the difference once, but right now I cannot even remember what it was without clickin

Somebody really should come up with better names. I know for a fact I knew the difference once, but right now I cannot even remember what it was without clicking the link. Surely many people who heard about this problem (and that's a lot of people, it's about as pop-mathy as it gets) don't even suspect these aren't synonymous.