Dear Christopher,
ECC stands for Enterprise Central Component.
ERP Stands for Enterprise Resource planning.
The below content is taken from wikipedia,
SAP R/3 is the former name of the main enterprise resource planning software produced by SAP AG. It
was renamed SAP ERP. It was later renamed Enterprise Central Component or ECC.
SAP is an Enterprise Resource Planning software.SAP ECC 5.0 ERP is the successor of SAP R/3
4.70. The newest version of the suite is MySAP 2005 or SAP ECC 6.0.
Regards
Mangalraj.S