Some variants have different species in its variant. However not all are different species, such as axolotls or cats, which each variant is the same species. However these mob variants are different species.
Frog[]
3 different species[]
Bullfrog (Brown Variant)
Green Frog (Green Variant)
Treefrog (White Variant)
Parrot[]
5 different species[]
Tropical Fish[]
2,700 species
2,700 different tropical fish species