Charles Thompson points out that different companies use the same names for different jackets. Unfortunately, the Black Tie Guide site has a couple of pictures that are not consistent with my understanding. The Regulation Doublet, for instance, is not just a PC with epaulets- it has Inverness Flaps (tashes) that seem to be missing from their illustration. There has been discussion elsewhere about single and double breasted Regulation Doublets and PCs, as well.

For some reason, Highland Clans does not show the double breasted Montrose doublet which is popular with many X Markers.

To avoid confusion, I have proposed a sort of menu of elements:

You can have your doublet to button or to be open.

You may have it with or without flaps/skirts/tashes.

You can have it single or double breasted.

You can have it with lapels or a military collar.

You can have it with any one of three styles of cuffs.

If you like, you can further specify the fabric and the direction in which the fabric is cut.

There are names for most of these variations, many of which are pretty well standardized among X Markers, but now and then something new comes along, or at least something named differently.

Double Breasted, no flaps, military collar: Montrose
Single breasted, flaps, military collar: Kenmore ( this is also a good approximation of a piper's tunic)
Open, DB, lapels, flaps in the back ( PC)
Open, Lapels, flaps all round Regulation (some would say this ought to specify double or single breasted, but I think they come both ways)
Closed, Single Breasted, lapels, flaps : Balmoral
Open/closed single breasted, lapels, no flaps Argyle/Crail

I am intentionally leaving at least one error in this list. I look to my superiors to locate it and point out my mistakes.