Japanese uses digits 0-9 for numbers like pretty much any other language around...

R = base model. Wet clutch, aluminum rims, non-adjustable suspension
SE = dry clutch, adjustable suspension, aluminum rims
SP = dry clutch,adjustable suspension, magtek rims

Magtek rims have a flat side wall, and say Magtek on one of the spokes.

of course it doesn't take much to turn an SE into an SP. Takes a little more to turn an R into an SE or SP but people have done it.

Basically it's hard to be 100% sure if it's a true SP, but if you got a dry cluch, adjustable suspension and Magtek rims and the bike is in good condition be happy...