I know the facebook for android app is the same as the one found in the market and, if I remember correctly, the HTC one is integrated with Sense on HTC's phones. The facebook for android app, while having the ability to sync with your contact list, doesn't really integrate very well and is really, IMO, just a good replacement for using the mobile browser (and has access to more features than using the browser) whereas HTC (again, from what I remember from when I was using Sense) included their app to integrate more with your contacts, but doesn't have the "facebook features" that the android app has.
