Hi, Aseprite is for drawing pixel art. It's useful for static pixel art or image per image animation.

Pixelover is useful to dynamically create animation already drawn pixel art (thanks to animation keys) and dynamically add effects to drawing or 3d models to "convert" them to pixel art.

In any case aseprite will be useful to create/edit pixel art by drawing. In an otherhand, PixelOver needs already created assets and it's more used for dynamic work.

So if you are new, I think Aseprite should be the best, PixelOver is more for a precise goal.