While people do notice faces and thus skin tone, one more obvious identifier, besides height, is gait and walk cadence.

Most foreigners will walk a different way from locals and it's really noticeable.

But dress is really important. Locals will wear some locally available brands, foreigners typically will keep on wearing the same brands they wore back home.

All that said, being 6'5" where just about everyone else is at least 6" shorter is a pretty unavoidable distinguishable difference.