Save adds the opportunity to your team's shared board, so everyone working on bids can see it.
Pass tells us you're not interested. It removes the card from your own feed and teaches the system what isn't a fit for you, so your future matches improve.
Archive is a column on your saved board. Move an opportunity there when your team has finished with it but you want to keep the record.
What about "Not Interested"? That's the old name for Pass. It does exactly the same thing — you may still see the older wording in places.
Both Save and Pass train your matching. Using them consistently is the single best way to make your feed sharper over time.