Translation
Translating means going from the source language to the target language with the use of computer-assisted translation tools (CATs), dictionaries, translation memory, etc.
Proofreading
Proofreading means comparing the source document against the translated one. Grammar, syntax, spelling, punctuation, and consistency are checked in order to produce an idiomatic text in the target language.
Editing
Editing is the process of examining exclusively a translated text with the intention of increasing its flow and quality in the target language.