Really quick and dirty, with lots of omissions:
ADL = internal magazine, no floorplate
BDL = internal magazine, hinged floorplate, usually better cosmetics
CDL = cu$tom $hop
DM = detachable magazine
There are variations based on:
- stock materials (hardwood, walnut, synthetics
- barrel profile (heavy, fluted, standard, light)
- rifle weight
- action/barrel materials (blued carbon, stainless, titanium (receiver only)
The Remington website isn't bad...it doesn't make it easy to compare multiple rifles at once, but if you click around in the 700 section you can pretty much figure out where a particular model is on the spectrum (spectra?).