Here's some comparisons of some different 121s. When I have access to my main collection again, I'll be able to post some photos of other 121s, including denver molds and the pleated skirt 121s.

From L-R:

California CD 121. The California CD 121s have a unique wire groove and wire ridges. The bottom WR flares out a bit, kinda reminds me of an early lilly shell multipart.

NE Duquesne 121 - This is a round dome variety, and features four ribs under the very square lower wire ridge. This has a very round dome.

Gayner CD 121 - This is the same mold as the Lynchburg CD 121s. These have a flared skirt and small, round dome.

NE AGEE 121 - This shows the shape of Australian CD 121s, with very rounded wire ridges and grooves. The sides and crown are very straight, with the dome being quite flat on top.