How would you be able to tell the difference?[/QUOTE]I guess it depends on how less advanced we're talking. I've been watching the shit out of Stagate SG1 on hulu, so when I initially read the prompt I thought of human like creatures that are simply less advanced technologically, as if in the dark ages or even cavemen or something. If that were the case, I'd want to help them and perhaps bring them up to a level similar to our own. Certainly not all at once, and not in a way that could bite us in the ass, but we could educate them, introduce modern medicine and stuff in exchange for resources.
If it's an animal life I'd probably want to leave them alone, or at least like any other wild animal we would encounter on earth. I'd want to impede their evolution and habitat as little as possible.
Between advanced aliens or alien animals?
I'd think it would be somewhat obvious I guess. I mean if they use some kind of tools, or perhaps something that appears to be a language or some kind of social structure. I guess the major flaw though is just if these aliens are in that stage of their development where the line between just being a really smart animal and being something mostly different is somewhat blurred. Like when humans stopped being really kick ass monkeys and start being humans, you know? So long as we don't encounter the aliens at that stage in their evolution and or development or whatever, then I guess we would be able to differentiate them from animals.
Plus if there's one type of alien animal on this planet, there would probably be others as well, so we would have something to compare them too a little better.