Every testing experience is variable, of course. I noticed there were many questions revolving around hormones. UWorld and even Kaplan didn't sufficiently help on that.
There's the obligatory Number Needed to Treat questions, which requires quick thinking (and therefore practice) that the Qbanks are weak on helping you with. The problem with the stats questions is that the answers will be very wordy (they go, "which of the following is true" and have big answer choices that suck your time up). So you have to read what the answer choices are actually trying to get at, find the number, and see what applies. Be superfast with stats. I'm actually good at stats, and I still ran out of time on a question because I didn't amp up my speed.
UWorld's heart sounds honestly are pretty lame, and Kaplan doesn't even have them. UWorld usually does S3, S4, or their valve problems are obvious in the question stem. That's not really the case on CK. You'll want to Youtube some of the valve diseases so you just have a good short-term memory of what you want to find.
Remember that UWorld cases will show up on the exam as seen, but not in the same format. You have to make some loose associations sometimes. I remember there was a Placental Abruption on UWorld presented as an auto accident. I think UWorld emphasizes the dramatic a little bit much. It's worth remembering that trauma is trauma, whether it's just a fall or it's a polytrauma car crash.
On the NBME's (and as well as on the CK), you might get unusual presentations for otherwise classically described situations. I'm pretty certain there was an elderly man with appendicitis on the NBME's, as well as a male Anorexic. Those do pop up, and UWorld doesn't help you on them too much.
Did you know long-term Rheumatoid Arthritis leads to atlantoaxial instability? I was blown away that this showed up literally everywhere I looked. Kaplan's QBook is where I first saw it. Then on UWorld, then Kaplan's QBank, and then... well, it's pretty crazy.
Derm photos are there, and UWorld does a fair job on those. They're inevitably going to show you something you have no idea about. But it seems like the trick is that they want to scare you with the wording. If something as simple as Herpes is mixed in with a list of Erythema _______, it's almost certainly going to be Herpes (just as a heuristic, not a law).
That's just some vague advice, just so not to give out concepts rather than answers. UWorld is good, and you'll see a lot of stuff word-for-word the same as seen on CK. Kaplan helps you read through the "what the heck are they getting at" moments. You're going to get stumped on a few things, and that's ok. Your goal is to minimize those experiences rather than unrealistically obliterate them.