Prosimians are a type of primate including lemurs and lorises. They are considered to be less developmentally advanced than monkeys and apes which are simply called simians. Anthropoids is another name for simians. This question is essentially asking How are prosimians like lemurs different from simians like monkeys?
Prosimians differ from anthropoids in their dentition or the teeth and their arrangement of the mouth and in the anatomy of the foot.
Prosimians have a tooth comb in the lower jaw composed of lower incisors and lower canines (Vaughan Ryan and Czaplewski 2000) which is missing in anthropoids while it is secondarily lost in the Aye-aye.
Prosimians also have a grooming claw on the second digit of the foot which is missing in anthropoids (Vaughan Ryan and Czaplewski 2000).
The tarsier pictured here is an example of a prosimian primate.
