PowerPlay.com provides online sports betting and casino services to players across the world. Deck Entertainment N.V. acts as the operator and is sublicensed by C.I.L.
Olybet.eu is a sportsbook, in-play bet market and an online casino. Of all these things, it is a sportsbook more than anything.
Casumo is licensed by the UK and Malta, which means it is not available to US players and a large number of other countries around the world. This is because of the stringency of regulations from these two licensing authorities, which in turn should give you confidence in the experience.
Bet365 is better known as a Sportsbook, and the bets offered on football and horse racing are why you would have visited the site before now. There is a good selection of casino games, and the bingo and poker rooms are worth a visit, but this is a sports gambling site more than anything.