Full-disk encryption is block-level encryption. If you're using TrueCrypt to encrypt anything, you're using block-level encryption. There is no functional difference between them. If you are not encrypting your entire disk, then block-level encryption is a bad idea because 1) it doesn't provide authentication, and 2) block-level encryption (using strategies like XTS) is not as strong as regular authenticated encryption using CBC and a MAC or whatever.

If you're not using TrueCrypt for full-disk or full-volume encryption, you'd be better off using basically anything else. There are plenty of cross-platform tools for doing that kind of thing.