Mechanical type

Dr. Gero is the genius scientist who created all androids. They are a cut above normal robots and have artificial intelligence and personalities much like human beings. Mechanical type androids are of machine type only. They are made of non-organic material and are created from scratch. The androids in this category are number 16,19 and 20 (all Dragonball Z). Number 19 and 20 have the ability to capture energy with the palms of their hands.

Biotechnological type 1

These androids are considered to be like cyborgs, they are combined with organic material and mechanical parts. Androids number 17 and 18 were created with a human base and are considerably more powerful than the other androids. These type of androids have a history of being difficult to control due to the combination of organic material and power cells being used. Android number 8 was commanded to kill Son Goku (Dragonball), but refused and became on the side of good. The same can be said of android number 17 and 18; they killed Dr.Gero, their own creator, when they were activated.

Biotechnological type 2

Not really an android, Cell is a organic creature created with the DNA of all the strong fighters that appear on earth (presumably with Son Goku and his friends/enemies). However, he does absorb android number 17 and 18 in his later forms, which classifies him in this category. The actual mechanics that allows Cell to absorb both androids is unknown. But one can make the assumption that he somehow plugs in the androids like an upgrade, absorbing their features and powers.