Most differences have been pointed out but there are a few more. The A7 is sort of a cross between the T3 & Sako 75.
The A7 bolt is very similar to the 75 where the bolt locks closed when on safety but has a second release button to allow loading unloading safely. The t3 requires the safety be taken off.
The A7 has 3 locking lugs like the 75, the t3 has 2. A7 has a 5 shot 1" guarantee, T3 has 3 shot.
A7 has what's called Total Control magazine, This requires upward pressure on the magazine while pushing the release, then it will drop out. Almost a two handed deal. Supposed to reduce accidental mag loss. Pain in the butt to me.
In the hand the A7 feel much better or more solid than the T3 lite. It also comes with Weaver bases mounted.
I think the smaller calibers allow top feeding but as the cases get larger the ejection port is more restrictive.
Last winter they were giving a $250 coat with thee A7. Prices have dropped into the mid $600 range on Gunbroker in the off season.