Both are used to record information onto DVD, films, data, photo etc. Depending on type DVD recorded to (there are lots different types) these can be played back on various sources. The advantage of a re-writer is it can re-record, eg record over the top of a DVD and reuse it. You do need special discs that are a little bit more expensive and to confuse the issue more, if you look closely at the burner its probably a rewriter as well