I own both, and have a lot of experience with both.
Both are excellent rifles - period.
Barrels on the Sakos and Tikkas are THE SAME. In fact, I may even make a post just on this point alone later on. When barrels come off of the factory, some go on Tikkas, and some go on Sakos.
The biggest differences seem to be in the components. Specifically, the Tikkas have much more plastic built in, whereas the Sakos have 100% stainless steel internal parts (on the SS models).
Triggers look very very similar, and both are adjusted from 2 to 4 pounds.
To me, the bolt action on the Tikkas are much smoother than the Sako 75. The Tikka's bolt just glides on the action. Still, the Sako action is world-renowned as one of the best actions.
Are the Sako's worth the extra $500 or so? Only you can answer that. I can tell you that, on the Deluxe models, the Sakos ARE better. Specifically, Sako uses something like 7 layers of coating to get that super shiny finish - that's high quality for sure. (I don't know how many the Tikka has, but the Tikka Deluxe is not a shiny as the Sako.) Also, on the Tikka deluxe, the bolt handle is silver, where as, on the Sako it is blued (which costs more money.)
Truth be told, if you shot both, you probably wouldn't be able to tell the difference in terms of accuracy.
Zachary