I am sure I’ve seen flavors of these product comparison search results in Google but the one Grant Oster shared on Twitter seems really new to me. It seems to compare not just pricing points but reviews, colors and more specifications between the two products.
Here is a screen shot from Grant:

Do you see the “highlight differences” toggle at the top?
I tried to replicate this myself but I cannot get it to come up for that query. In addition, it is not clear if this is from Google Shopping results or if they are core web results. I see no mention of ads or sponsored listings on this screen shot.
Forum discussion at Twitter.
Update, I was able to bring it up for this query and made an animated GIF of it.

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