I haven't done Water Country, but I've been to BGW a ton of times.
It's not as animal focused as BGT, which makes sense when you remember that this is themed to Europe and not Africa. They do have animals at the Highland Stables, Wolf Haven, Eagle Ridge, and Wild Reserve (and typically have photo ops with eagles, clydesdales, and various critters at Wild Reserve, plus have sheep herding exhibitions). The wolf training tour is fantastic if you have anyone in your group that loves those; an animal up close tour for various animals at the Reserve; or a clydesdale/collie tour for people into those (they're $27 each per person). They also do a combo of all 3 tours for $55.
Mach Tower wasn't open when I went last (which apparently is a common occurrence, so I wouldn't get my hopes up about riding that one), and Verbolten is new (but my mom *LOVED* it ... stay away from any info on it if you don't want the surprise ruined), but I've been on all the other coasters multiple times.
Alpengeist is like Montu; Griffon is like SheiKra; Loch Ness is kinda like Scorpion except it goes upside down twice and has shoulder harnesses. Apollo's Chariot I don't have anything to compare it to, because it's a hyper out and back, so it's just fast and lots of air time (no loops or twists) and really tall; back row for that one is a must.
Curse of DarKastle is like Spiderman; Escape from Pompeii is like Splash Mountain/Tangyankia Tidal Wave; Le Scoot is a typical log flume; Roman Rapids is like Congo/Kali/Bluto's; there are a few amusement park staples like a swinging ship (like the Phoenix at BGT but doesn't go upside down), a sandstorm ride, a music express, teacups, wave swinger, bumper cars, etc.
The biggest difference will be walking. Oh, the walking you will do. And the *HILLS*. You will definitely feel it the next day. But it's nice and shaded, so it feels cooler than it is (we typically did BG and King's Dominion when we went up there, and the days at KD just were soooo much hotter than BG), and the park is GORGEOUS. There's a reason they've been voted "Most Beautiful Theme Park" for something like 18 years in a row.
Oh, and the Land of the Dragons has a fun rope climb area, kinda like the one at BGT and SW. It's themed really cute, too, so the girls might like running through there to burn off energy if you decide to take an ice cream break during the day.