Farley's Follies

Daniel Gasteiger

Could someone help an old guy out? What are the actual differences between "Farley's Follies" stamps and the regular sheets, singles, etc. I am unable to detect the real differences?
Thanks

George DeKornfeld

Less typing if I just provide a link:

https://www.mysticstamp.com/info/what-are-farleys-follies/