Do the shear plates have the ribbing to shear off the fuel from the walls?

I don't know exactly as to what is going on, whether a boundary layer is being created or whatever. Some spacers will have a smooth tapered surface, others are machined with steps. Everyone has a different way of thinking. In many cases, I believe it comes down to what might be easy to machine, or as silly as it sounds, what is visially appealing to the purchaser.

"It appears the anti-reversion plates have a trough around the openings to reverse the direction of flow."

Most that you see will have that trough or groove that you are refering too. I have been meaning to test without it, or adding a pocket instead

The other ones posted look like a diffuser style with a tapered opening. A pressure recovery like the downside of a venturi.

I think Darin Morgan described them best, by refering to them as transition spacers. A means of transitioning from the carb to the manifold

Does that summarize the differences?