There are Long and Short length-of-pull modules. One is Low height for shooting with irons, and one is High height for using a scope. The Standard rifle comes with two Long modules, one High, and one Low. The Compact rifle comes with two Short modules, one High, and one Low. Any of the modules can be fitted to either rifle. It's easy to buy the desired modules from Ruger, and fit them to a rifle. For example, fitting a short module to a standard rifle so a kid could use it. Just keep the included Long modules so they can grow into them.
To keep the price as low as possible, Ruger does NOT include the Weaver scope mounting bases with either rifle. They are not hard to get, and not at all expensive. The top of the receiver is drilled and tapped for these bases, but the holes are filled with screws which can be easily removed.
The full size rifle will have a longer iron sight radius, and perhaps a bit higher bullet velocity than the compact model.
It will also have a slightly different point of balance, but adding some weight to the inside of the hollow buttstock allows the user to customize this. The compact model might be handier to carry in the brush, and easier for kids and very small adults to manipulate.
The newer versions of both rifles can be had with threaded barrels, and come with thread protectors. For folks planning to install sound suppressors, the obvious choice would be the Compact model. It might also be possible to install a flash suppressor on the threaded barrel of either rifle, but it's doubtful if either rifle really needs such.