Is Captain Marvel (Marvel) not just Supergirl?

I love Supergirl, but the two, aside from their last name, are nowhere near the same.

Kara's energy projection is limited to heat vision, and her energy absorption is limited to yellow solar radiation. Without this, she reverts to the abilities of a normal human.

Captain Marvel can a multitude of energy types, and use it to temporarily increase her own abilities. She can augment her strength and energy projection up to the force of an exploding nuclear weapon. And even without aborbing energy, she retains an incredible amount of super strength, speed, durability, and stamina. Meaning that her abilities aren't dependent or effected by what type of solar radiation she's currently under.

This speaks nothing to the different types of characters they are, outside their hero identities. Kara's an alien refugee. Carol is kinda the opposite. Her DNA was spliced with that of an alien. And she started out as Air Force, who, through a series of events, was brought into contact with the alien race that lead to her transformation.

There is a lot more detail than I know, but that's what I can remember based on comics I've read, animation I've watched, and some brief online research.

There are some Marvel characters who are remarkably similar to Superman, but none, off the top of my head, that correlate to Supergirl, in such a way.