Well...Every brand uses different length, designed, and shaped actions.
Remington 700 rifles only have 2 different options, as far as the action length is concerned.....They offer "short-action", and "long-action".
Now, once you get down to the 2 basic action lengths, you break it down by bolt-face diamter of the caliber you want to shoot, those sub-categories consist of:
1) .223 / 5.56x45 bolt-face
2) Standard bolt-face (.308/.30-06)
3) Magnum bolt-face (Rem Mags, Win Mags, STW's, and RUM calibers)
4) Short-Mag bolt-face (SAUM & WSM calibers).
5) Misc random NATO calibers and other odd-ball caliber bolt-face diameters, such as 7.62x39.
Examples of "short-action" calibers: .223 Rem, 22-250, .308 Win, 7mm-08 Rem, .243 Win, .260 Rem. Those are all good classic examples of short-action calibers.
Examples of "long-action": 7mm Remington Magnum, .300 Winchester Magnum, 7mm STW, 8mm Remington Magnum, .270 Winchester, .30-06 Springfield, .25-06 Remington, .257 Weatherby, 7mm Weatherby, .300 RUM, and the list goes on and on...
Now, different calibers require different modifications done to different parts of the action. For example... The Remington Ultra Magnum calibers use a standard 700 magnum bolt-faced long-action. However, the feed rails inside that action are opened up wider to accept the fatter cartridges so they will feed right and reliably.
As you can see, it's pretty straight-forward for the most part. But you can break down the short-action and long-action calibers by bolt-face as a sub-category to determine what caliber you plan on shooting.
Example, say you want to shoot a .270 Winchester, and you want to build a custom rifle
. You would look for a long-action with a standard bolt-face. Which means it would have a .473" bolt-face, the same as a .308 Win, and a .30-06, 25-06, or any other caliber based on the .30-06 cartridge, regardless of caliber length.