Title says it all.

A short block has just the pistons and cylinders installed on the block/crankcase, but no cylinder heads with it. A long block typically refers to an engine with the heads attached to it. Neither one comes with the intake or exhaust manifolds or any part of the cooling system (Fan and cooling tins).

And an engine that comes ready to plug and play is a crate engine.

Long block, short block, crate engine are all terms that are used improperly in the automotive industry.

Short block originally meant block with internal rotating assembly installed. Just crank, pistons, rods. No cam, lifters, pushrods etc...
Also, no oil pump, timing gears, covers, etc...

As you can see this is NOT how a air-cooled Type 4 would be sold as the cam, drive, and oil pump are integral inside the split cases we have.

A long block would come with the short block assembly and heads, cam, cam drive, valve train would also be included. A Jasper rebuilt engine comes this way.
It doesn't have oil pump, valve covers, or oil pan installed. Normally the oil pump is included but not installed. Most of the time the front engine cover is also not included or installed except where it is a major part of the engine (Ford modular V8/V6s have this installed as a long block).

A crate engine can be anything, you could have a "crate short block".

The ATK long blocks used to come with everything. valve cover to oil pan. They were also in a super nice crate...

The VEGE engines we sold (German re-manufacture) were complete as well. They had valve covers on them and just required intake, tin, and exhaust to run.

I've never seen a rebuilt engine come with a distributor except the "complete" GM crate engines. Some of those came with belt drives and accessories as well.

And then there are "production line" engines that were taken directly off the assembly lines with almost everything on them. GM sold a bunch of engines this way. These puppies are complete including alternators and AC compressors, coils, injection, and wiring harnesses. Just like they came off the assembly lines as they really were.

At one time I was offered complete LS6 engines for 2K a piece!!!
You had to order 5 to get that price.
10K was too much for me at that time but I wish I'd bought those now...

Thanks for enlightening me.

Thanks for your info as well.

I've been more familiar with the GM crate engine that is as you described.

My experience mirrors what you described: I had my new Z06 (April 2006) drop a valve (the curse of the LS7) when it just had 4k miles on it. it happened on a Sunday, next day the dealer was telling me their complete engine replacement program ended the previous Friday.

The engine replacement program would have pulled an engine off the assembly line as you said.

Instead I got a long block replacement, which means all the accessorials (AC, Alt, intake, exhaust, coils, what you said) were to be reused from my car.

The LS6 was kind of an ugly duckling; only used a short while. This could have been why you were getting the deal. Ugly duckling or not, LS engine...you could have easily got $30-40k out of those engines.