Is there typically any difference in a left hand doulble rifle and a right hand double besides perhaps some cast-off in the stock or which side the cheek piece is on? Are the triggers or any other part of the action different?

The answer to your question is variable.

For instance, there are complete left hand rifles which are mirrors of right hand rifles, with the top lever opening the opposite direction, ie drawing to the left, the front trigger being the left trigger, cast on for a lefty and a cheekpiece for a lefty.

There are left handed rifles which have right handed drawing top levers but front trigger left barrel too.

And then there are adapted left handed rifles where the top lever draws right and the front trigger fires the right barrel, but where the triggers are twisted for a lefty, and a left handed stock.

I'm a lefty and since all of my SxS shotguns are right drawing top levers and front trigger right barrel, this is how I prefer my DR's. The stocks accomodate lefties, the triggers are twisted to accomodate lefties, but the gun is at core a right handed version.

Edited to add that so long as a right handed rifle does not have an extended top strap, or more than about 1/4"-3/8" cast off, it can ussually be bent to provide 1/4"-3/8" cast on for a lefty. So a great cnadidate is a rifle with short top and trigger tangs (or straps in Brit) and no cheekpiece. Twisting triggers is a cheap and easy job for a qualified gunsmith.

JPK

I bought a used right handed double rifle. I sent it to the manufacturer to have a left handed butt with a left handed cheek piece installed. While they had it they turned the triggers to the left for me. It cost me $650.00 to have this done and they kept they right handed butt that they changed out. The rest of the gun seems natural as that how all of my shotgun work.