COMPUTER HARD DRIVES
touch screens are basically a thing that lets you do it with your fingers e.g. zoom in or show the directions with your fingers telling it.it basically means that if you swipe the the screen to the side then the screen will come along with it.the first touch screen maker was steve jobs who made i phone 3g.
computer hard drive
hardrives are very usefull because the more gigabytes or tera bytes you have, the better it is for your system to be very fast and easy.if your computer is loaded with pictures or other stuff then your pc or computer will be slow and then your whole system will be slow and then you can not really do any thing.basically external means it is seperate and internal means that it is in your computer or your pc.