Perhaps it is! I wouldn't claim to know all of the worlds' secrets, after all. Terra, Earth...perhaps they are simply one and the same.

[Honestly the REAL answer is that Terra is probably a post-apoc version of Earth to begin with but hey, Vash would probably know what that's like!]

Haha! Oh, my friend...I know plenty. You wouldn't imagine the chafing when the sand gets caught beneath one's armor, or in the grooves of your tail.

[He wiggles his little dragon tail for emphasis. Vash probably cannot relate.]