The difference between duplication and replication can best be understood if you know how many copies you need. For instance, 100 copies would best be handled by CD duplication. That is, to take an existing blank disc and burn the content from the master to the blank. This is what we can do at home on our computers.
Now if you needed 1000 then CD replication is the best option. To duplicate 1000 blank discs is just too labor intensive even with automated duplicators. The only cost effective way is to make a glass master and press out discs.
This is not something you can do at home. You will need to work with a CD duplication company that can provide this for you. You may have noticed there is a lot of room between 100 and 1000. Is there a point where CD duplication and replication costs meet? Yes, there is and it does vary but generally speaking once you get over 300 duplicated CDs, you are coming to the costs to replicate. What this generates is a no-mans land between 300 1000 where its just going to be based on factors other than price as to which method is best for you.