>>9732289SO-DO uses hard plastic, has show gimmicks and uses stickers. SHO-DO uses some softer plastics/rubber with shoulder pads and any scarfs/skirts, usually has low to no stickers and usually doesn't bother with gimmicks. They are both general releases, but both also get p-bandai releases.
You didn't ask for it but I will also just say, YU-DO is the Sentai variant of SO-DO. Although recently Bandai has been releasing full teams under a line called SHO-DO SUPER. CHO-DO is the Ultraman variant of SHO-DO when Ultras split from the SHO-DO line.
Pictured is a Converge, SHO-DO, SO-DO, and a YU-DO.