|Look at the face of the drawer on your CD/DVD drive. Does it say DVD-RW? If so, it's a DVD burner.|
If you're asking about copying store bought DVDs, the standard movie DVD holds about 7GB. Burnable DVDs only hold 4.7GB. So to make them fit, you need to use compression software. You can also rip out all the extra crap (previews, deleted scenes, interviews, etc) & burn just the movie.