As far as I know there shouldn't be a difference. I own a 700 ADL and from what I've read it's just the rifle being named SPS and the stock having some cosmetic changes.
But why, besides economical reasons, would you want a synthetic stocked .22-250? Why not spend a few more bucks and get a VLS or a match grade rifle? I assume you're going after varmints...that VLS might have the accuracy ya need.
Have fun! Sorry it took this long for a response.