The rarest of the three classes, users of Logia Devil Fruits gains the abilities to transform themselves into an element. They also gain every ability related to that element and gains the skill to regenerate every part of their bodies from that element. Logia users can increase and control every part of their transformed bodies into elements and control and make their elements.
The most common of the three classes, users of Paramecia Devil Fruits gains super-human physical abilities. Other users can alter features of their bodies or their environment. Finally, there are some users than can manipulate and generate some kinds of substances.
The users of Zoan class Devil Fruits gains the ability to transform into an animal (and acquire every ability affiliated with the said animal). The user can also transform into a human-beast hybrid form. There are Zoan Devil Fruits not only for common animals, but for prehistorical or ancient animals and mythological creatures as well (ancient and mythological are rarer than logia).