This picture shows two different categories. Moss Agate patches on top to the right of center. Ace corkscrews on the bottom right. So it shows that in one way that the Ace bases can look similar to the white-based moss agates. But there are differences also.
The moss base is very smooth in consistency.
The Ace base is a little more spongy and sometimes you might see a grain in it, like with an Acme Realer. It's supposed to have an orange glow inside when held up to a light, like with the Acme Realer. But I don't think it was consistent. The base could be very dense, or it could be very wispy. Too dense you and don't get enough light through for the glow. Too wispy and you might lose the glow for a different reason.
I don't think the Ace lasted long as a production item. The Moss Agate lasted for years and years. There were swirl and corkscrew versions, not just patches.
There really aren't that many clearly identified Aces floating around. There are a lot of Moss Agates. And some of the Moss Agates get called Aces.