IIRC:
"P" = ported (barrel), in the case of the M1894, a 16 1/4" bbl.
"C" = .357 chambering
"D" = .41 Mag chambering
"L" = 2/3 length mag
"CB" = Cowboy model
"S" = Sporter
"SS" = Stainless Steel
"LTD" = Limited (Edition)
I'm sure there's some I've missed.
AFAIK, The variations of M1894's have had barrels of 16 1/4". 20", 22", 24" - a couple of the lengths as octagon configs ILO round.