CIP is the NACE coating inspector series. These are the guys you hire to watch the paint being applied (and all the associated activities, such as surface prep.)
A full fledged inspector is Level III. NACE expects lower levels to work under the supervision of a Level III - though in the real world, plenty of Level I and Level II work on their own (or just have the cert and are really a sales guy or something)
OCAT is more asset management/in-service inspections.