Few differences (we also have a lot of respect for RF, those guys have a great product):

- Verified actions, we verify via API's that users actually complete an entry. You can just bypass this on RF (something I'm sure they're working on).

- API, you can create completely custom entry types on Gleam. Put our API code on your shopping cart, or email signup form & activate an entry. Useful for things like "Add 5 products to your wishlist for an entry, or leave a review for an entry".

- More social network coverage (Instagram, YouTube/Soundcloud)

- More ways to install than just embedding on the page

Looking at rafflecopter, they power plain giveaways. Give me your name, you get the chance to win something. gleam.io seems to be more for competitions where users can do different stuff to get multiple entries. Quite a different product.

RaffleCopter only offers giveaways, and does not have as much features as other competitors such as Splurgy, OfferPop, etc...