Another "learn me" question

jkrk

I've been buying double eagles for about 8 years and never used "the pricing info (guides).

I noticed greysheets and blusheets data recently and I was wondering about the difference?

I read that Bluesheet prices are for sight unseen coins. Gresheets are for slabbed or raw coins that are seen in person.

Am I on the right track? I assume they are still widely used?

I understand these are guides and markets change rather quickly but now I notice the estimated pricing and use them for one extra data point.