User blog comment:Kogath/Monster Hunter X Discussion/@comment-26552205-20150630221247/@comment-5167887-20150701121544

Steve and his brother-in-law don't have the same head structure, wing structure (we call the new monster Dragonfly) nor the same body structure. Steve seems bulkier than Dragonfly and he shows the ability to raise its scales on different parts of its body whereas D-Fly doesn't show any similar ability.

They're obviously in very different families, thought both of them being flying wyverns.