come on man! Do a search on the Internet, or even
http://www.srswap.com or phase2.
Well, the difference between a clip is that the clip, as its name implies, is the whole front clip of the car, from the A pillar and onward. It is the front half of the car. Clip is complete. Most of the time, it comes with JDM or other Asian market body panels, such as lights, fenders, hoods, and bumpers. But those items are usually removed from the sellers. If you are lucky, a clip might even come with some brake upgrades, front coilovers, a nice strut bar, or other upgrades. A clip is guranteed to come with the entire engine with turbo and extension (downpipe might or might not be included), ECU, transmission, MAF, igniter chip, alternator, starter, dash, intaker box, spedometer, radiator, brake cylinders clutch cylinders, uncut harness, intercooler, plumbing, heater core, etc, etc, etc. In addition, the clip also comes with some suspension arms and members, steering tie rods, brake calipers, and rotors. The clip also comes with fender liners that are vented to cool the front brakes.
A complete engine comes with just an engine, transmission, ECU, harness (cut or uncut depending on sellers), igniter chip, alternator, starter, MAF, and some piping required. It doesn't come with intercoolers and intake boxes. Most of the time, it doesn't come with a downpipe.
The good thing about getting clip is that it usually protects the engine's oil pan. Since the engine is inside a clip, the oil pan wont get banged up during shipment.
These are some basic stuff, please fill me in if I am missing anything.