BUPC Optical Drives
Blu Ray or DVD-Writer
Select either a DVD-Writer or a Blu Ray Drive. You need this to read or write CD's, DVD's or Blu-Ray Discs. A DVD Writer can work with CD's as well as DVD's. And A Blue Ray Drive can work with CD's DVD's and Blu-rau discs.
Few Products having 'external' in their name - are external drives - connected to the USB Port of the PC or laptop. Since You are Building Your PC, you should go for one which is not an external drive. Select one without 'external' in it's name.
If you maintain many systems, You may consider buying an external drive for multiple machines instead of buying one internal drive for each of the machines. If you travel a lot with your laptop, you may need it as well.
If You are building a Server, You may find it more secure to use an External Drive.