Err ... what?
Lions and tigers aren't different species. Where the hell did you hear that from? And "humanoid" has nothing to do with species.
Lions and tigers are in fact different species. But it's a little-known fact that almost all cats can interbreed, and the female offspring will usually be fertile. Doesn't mean they aren't separate species--the male offspring are sterile, after all.
Not only are there differences in outward appearance, but also musculosckeletal structure, behavior, oh and geographical location--they are geographically isolated from one another. They're related, but definitely separate species.
All "humanoid" means is "resembling humans." Technically turians are humanoid. So "humanoid" doesn't mean "human."