Which files do I transfer, Zip or scriv file extension?

Scrivener Scrivener for macOS
1

I reimaged my iMac, and noticed my Scrivener project has two sets of files with same create/modified date:
FILENAME-bak.zip
FILE NAME.scriv

  1. Other than the Zip version being more compressed, would everything else be the same (e.g. application settings, list of documents in Research Folder etc.)?

  2. If I carried over the .scriv project, but I wanted to use zip compression, is there a way to convert the .scriv to .zip, or do I need to just apply to next saved version?