Anything can be an alien! That's going to be determined by the context of the story -- tell us the character is an alien, and we'll believe you. If you want an alien character to read as alien IMMEDIATELY without anyone saying they're an alien, you kinda have to lean into stereotypes. That can be good character design if that's what you want, but it can also be sort of boring character design otherwise.
But tweaking character design isn't about small things like changing a single line. I had to go back and forth between these to see what was even changed -- a lil circle at the end of the tail, one eyebrow line instead of two, the pupil is a slightly different shape -- stuff like that doesn't really change the design of the character. Think about it -- if you took a picture of Mickey Mouse, and then you changed the shape of his pupils and gave him angry eyebrows, it wouldn't stop looking like Mickey Mouse, because he has the same silhouette overall. It's if you made him taller or wider or changed his ears in a major way, you'd end up with someone who looks like a different character.
But overall, these are fine, and for a comic with a simple style, I think they can work! If you wanna push them to have more distinct designs from each other, I think you could push the shapes so that the two of them aren't just the same shape with different accessories, but that's not strictly necessary. I think it'd be worthwhile to draw more than just the one pose, and draw them in different expressions, because figuring out how they move and what kind of expressions they make will develop the design too!