Basically boil sugar and corn syrup, combine with dissolved gelatin, and whip it until it's light and looks like marshmallow fluff, then let it cool. Recipe if you're interested. I do recommend having a stand mixer with some good power for it to work or they won't get fluffy enough before the mixture cools.
If they get fluffy enough, the texture is about the same as the store bought and maybe even lighter. If not they kind of taste like marshmallow flavored jello, which isn't that great. Still works for rice crispy treats though, so that's always a good backup if they don't turn out.