They are one in the same. The 40x is supposed to be held to tighter tolerences, however I have seen some 40x's that didn't shoot for crap. This had to do mainly with the barrel, it seems Remington has gotten pretty sloppy with their chambers. IMHO I would save the extra cash and go with the 700 action and get it squared and lapped, usually the 40x actions cost quite a bit more.
well about the Remington 40-XB Tactcical it looks like every one of them is a sweet shooter off the assembly lines if they live up to thier guarentee... comes with a test target so it should
the one i shot was great but so were some Remington 700s (including the one i own) which cost a hell of a lot less
just Remington Custom shop gives it a 3/4" 5 shot group @ 100y guarentee while Remington Law Enforcement gives the same rifle a 1/2" @ 100y for a 5 shot group guarentee and a 3/4 moa guarnetee on the same page!!!
seems like Remington cant make up thier mind
40X actions also have a different/better trigger group.
I noticed the confusion on what the guarantee is suppose to be, it USED to be (several years ago) .5" groups, but it was caliber dependent also. Magnums got the .75, perhaps thats the way it still is, but remington has just not clearly gotten that info out.