The order Columbiformes comprises a single family (Columbidae), which includes over 40 genera and 300 species of extant pigeons and doves.
Pigeon and dove can be used interchangeably, but it is often the case that dove is for smaller species and pigeon is for larger ones.

Pigeon is a French word that derives from the Latin pīpiō, for a "peeping" chick;
Dove is an ultimately Germanic word that refers to the bird's diving flight.
A group of doves is called a "dule", taken from the French word deuil ('mourning').
Middle English: culver, from Old English culufre, culfre, culfer, possibly borrowed from Vulgar Latin *columbra, from Latin columbula (“little pigeon”), from Latin columba (“pigeon, dove”).
Columba: Latin columba (“dove, pigeon”). Ancient Greek κόλυμβος (kólumbos, “a diver”), from κολυμβάω (kolumbáō, “dive, plunge headlong, swim”).