At this point in their careers, Moss and TO can probably provide similar skills and experience. But the difference is the Niners were proactive at signing Moss and allowing him to aid in the development of the entire WR before FA period began, giving them an ace in the hole for FA and the draft. The Seahawks, on the other hand, don't target the position until camp. Realize that Mike Williams can't make the cut, then scrambling to sign Edwards and TO; essentially the Seahawks were being reactive whereas the Niners were being proactive.
The difference is a front office that knows what it needs and knows when and how to secure the assets necessary to be successful. In a copycat league, they get copied, not copying others!!
In Harbaugh We Trust!