Re: hard disk
1- Portable hardrive(r) in which you can play a CD/DVD. Some of these also use to burn CD/DVD. Burns mean recording 
2- Portable hardisk is like ‘USB’ where you can store data. Protable hardisk is fixed with disk that is not changeable.
If you want to keep your data i.e. files, videos, images etc in different CD/DVD than go for option one. U’ll have to buy empty CD/DVD.
If you want to just transfer all data into another storage device than go for option two.