Frogs and Toads

Know-it-alls often ask what's the difference between a frog and a toad and give you a smug explanation when you can't answer.

Scientifically, the difference between frogs and toads isn't so straightforward. Many anurans (members of the order of tailless amphibians) have characteristics of both toad and frog. Some have traits unlike either such as marsupial frogs.

The semantic problem came about because in Europe two of the most frequently encountered, and therefore named, anurans are Rana temporaria (the common European frog) and Bufo bufo (the common European toad). Because European languages had separate words for toad and frog, the difference spilt into scientific terminology. The varied anurans in the rest of the world were expected to fall in line behind the European species.

So the true difference between frogs and toads is largely artificial and we can blame any difficulties on the EU.
(Mattison, Chris. Frogs and Toads of the World. London: Blandford, 1992.)