Really a pretty open question where we compare the apple and the orange.
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Both rifles are gas operated and both rifles can be scoped easy enough with the AR 10 (Top) being the easier of the two to place optics on. The pictured AR 10 has match sights but can easily be scoped or returned to standard iron sights. The scope and sight configurations for the AR 10 look like the below image.
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The pictured M1A is a NM (National Match) rifle with iron NM sights, front and rear. Both rifles are capable of sub MOA groups with match grade ammunition. While the M1A can be scoped the rifle itself was never designed with a scope in mind and most mounts tend to come loose, that said there are several good reliable mounts for the M1A design. Both rifles are shot in long range competition out to 1,000 yards. It becomes a matter of personal preference. Also, as a side note the name AR 10 is exclusive to Armalite much like if the rifle is an AR 15 it is Colt manufactured. Armalite sold the AR 15 naming rights to Colt Manufacturing. This is why we like to use terms like AR 10 "platform" or AR 15 "platform". There are a few versions of the AR 10 platform which do vary. Just for a quick example not all AR 10 magazines are the same or interchangeable like the AR 15 flavors.
As to accuracy? Both of my rifles shoot about the same and both are NM rifles. I likely enjoy shooting both equally so I have no favorite. Configured for match there is not much weight difference and the AR 10 with the floated barrel and aluminum handguard likely weighs more than the M1A. However, you would configure either for your likes and dislikes. There really is no saying either the M1A or AR 10 is the more accurate of the two, it's a matter of barrel, parts, sights and what you decide to buy.
Least I forget the pictured rifles are both over 20 years old. When I bought and modified my AR 10 Armalite was about the only guys on the block. Today there are likely a dozen manufacturers hawking the AR 10 design in a few flavors. I like mine but again, when I got the rifle the field of manufacturers was very, very limited.
Ron