An Implementation Engineer deploys a system (usually software, but not always) in a customer's environment. The deployment may involve the creation and installation of add-on components specific to customer's needs in addition to the core ("off the shelf") product that is installed during every implementation.
An Implementation Engineer may perform these activities:
Relationship to other positions: An Implementation Engineer and an Integration Engineer perform similar activities. However an Implementation Engineer focuses on the internals of a particular application instead of the communication/data sharing between multiple applications.