Not sure how well the search function works here (don't really use it) but you'll find this topic is discussed a ton. We're huge fans of both, and in short I'll say that they're both fabulous. You won't go wrong at either one.
The biggest difference between the two is the wave pool. BB has smaller, constant waves. TL only has waves every 90 seconds or so, but it's one MASSIVE one. Both are zero entry pools, so you can bring young kids into either, just keep them in the shallow end if they can't swim.
Both have thrill slides. TL has Crush Gusher, sort of like a tube slide roller coaster...jets of water push you up a small hill, not just down. It's not THAT fast, but it's really fun. BB has Summit Plummet, a huge drop slide. It's awesome and fast. It's also wedgie inducing.
Both have lazy rivers, which are fun. Both have family tube rides, the one at BB can hold more people (7 I think) vs TL (4 people), but TL has two of them.
You don't need to show up extra early at either. They usually open at 10am. If you show up at 9:55am that's more than enough. You can ride anything you want with no wait for about an hour, before lines start to build. They both have more than enough chairs with shade for free that you won't have trouble finding a spot. Yes, they have cabanas to rent, but IMO they're insanely expensive...like $350.
The pavement can get hot, so be mindful. They hose down most of it, but it'll get hot in spots. I despise water shoes, so I won't wear them, but some do to help with that.
Both have kiddie areas. The one at BB is a bit better defined and has a few more activities, but the one at TL is nice too.
There are stairs...lots of stairs. Be prepared to climb if you want to go on the big slides. We usually stay for 4 hours or so and are done.
They are SO much fun.
