A little while ago I was trying to understand the same thing and eventually came across UWIN33 Malaysia https://u-win-33.my/ . What I liked was that the platform separated free credit, voucher codes, and promo codes instead of mixing everything together. I also noticed there was information about where offers appear and how some codes can be connected to ambassador campaigns. The explanations about expiry dates and bonus conditions made things easier to understand for me. Compared to some other sites I checked before, this one felt more organized around explaining the differences. Personally, I found it useful because I had the same confusion before.