Is there a difference between an external backup and an external hard drive?

I want to take all my iTunes and photos off my laptop and store/access them externally because they're really clogging up my computer.

I purchased a 2 TB Seagate Backup Plus Slim.  If I take iTunes/photos completely off my laptop and put them on this device, will I be able to access them as if they were still on the laptop, i.e., get my regular podcast downloads and then download them to my iPod?

(Hope this makes sense)