"Elephant ear" is usually used for Alocasia, Colocasia and Xanthosoma, and occasionally for some other closely related genera. The name comes from the ones with the big leaves--and some of them get enormous--although all three genera have smaller members.

Caladiums are closely related with similarly shaped leaves that are are much more colorful but generally much smaller. Most caladiums will have leaves about a foot long or less, and usually don't grow more than a foot or two high.

One big difference is that caladiums are true tropicals and cannot tolerate any cold temperatures. They start to go dormant as soon as temperatures start to drop in late summer. Alocasia, Colocasia, and Xanthosoma seem to be more subtropical and will tolerate some cold temperatures, although they will stop growing. In my garden, most elephant ears look good right up until a frost kills them.