I would think that the difference is: if it's not listed as "mil-spec" then it was made by a company that was just duplicating mil-spec paracord, without regard to the actual specifications (as listed in the previous post). So, it may not be quite as strong, i.e. it may not have been tested for strength and durability, it may not have the same quality of nylon, same consistency in color, etc.etc.

Probably for general use it would be allright but "mil-spec" doesn;t cost much more, if any, that I've noticed, so I stick with true 550 paracord (or at least that advertised as such).