You bet!
The first two are portable hard drives. Meaning that they run just off of USB power and are a lot smaller and easier to carry around. Between the two, the second one has a Firewire connection, which can be faster than USB 2.0.
The final hard drive is a larger version of the first two that requires a wall outlet to use it. It also has Firewire like the second one though, so if your computer has Firewire, it may be worth a look.
