What do you mean by pre-print and post-print?

Pre-print usually stands for the first draft of a paper submitted to a journal before peer-review. Definitions vary for post-print. The two most common definitions for this version are:

• The full, final version of a research paper as formatted by the journal publisher. This version generally cannot be uploaded into a subject or institutional repository.
• The final, edited version of a research paper, after peer-review and any subsequent changes are made but before formatting done by the publisher.