To duplicate or replicate?
There are two ways you can copy cd or copy dvd, namely CD/DVD Replication or CD/DVD Duplication. Replication means the disc will be pressed from a glass master and the artwork will be printed directly onto the disc surface just like any CD or DVD you find in retail stores. Duplication means the disc will be burned from CD-R or DVD-R media and the artwork will be printed on a paper label which is then applied onto the disc surface. Duplication is synonymous to CD burning or DVD burning.
If you have enough time and the ordered quantity is 500 or more you should always use CD replication or DVD replication. The only time you would resort to CD duplication or DVD duplication is when your order is less than 500 or you need to rush the order. In that case you should use CD duplication or DVD duplication.