save conflict occur when two or more users edit and save the save document on the same server at he same time. you can use the document lock to reduce the save conflict.
replication conflict occur when two or more users edit the same document on replicas o the same database on different serves in between replication events. Domino can merge the replication conflict at some condition, or can let user to handle.In real environments, we can not thoroughly erease the replication conflict, but with reasonalbe domino setting and archi ,we can reduce it .