Sako rifles have a one-piece bolt, and a better extractor. The Tikka has a 2-piece, with a plastic bolt shroud (seen more than one broken one). Sakos have metal floor plates,trigger guards, and magazines. Sako offers 5 different action sizes, so the action is caliber specific, not having to use an oversized action for a shorter cartridge. Tikka uses 3 different actions. Sako guarantees 5 shots in an inch at 100y, Tikka guarantees 3 shots in the same inch at 100.
Also one of the major differences is the scope rings. Tikkas are 1-piece aluminum, fitted to their groove. Sako rings are steel, and are screwed to the solid steel Opti-lock bases-one of the best systems in the industry that I have ever used.
As you might imagine, resale value of the Tikka is nowhere near the resale of the Sako.
With that said, both rifles wear hammer-forged barrels, and are extremely accurate. Lighten up the trigger on a T3 and strap a nice piece of glass on it, and you have a very accurate rifle.
Hope this helps.
M22