Paramecia fruits vary a whole lot. Basically a df eater who is a paramecia type can project, turn into or manipulate a certain thing but not all at once. You'll be able to tell if someone is a logia type or a paramecia if
1. Their power is based on an element found in nature.
2. They are able to change their body, project AND manipulate that element.
Alvida, Buggy and Luffy are paramecia types cuz they can only affect their own bodies.