Wel the R2 does have more of a rounded nose,and the R1 is just a little pointier...someone else who knows more about them can tell the diffrences in a more detailed manner,im just going by what i see.
Well, the M-250R1 (labeled in the GE catalog M-250R) was a bit longer than the R2. It indeed had a flatter profile and appeared to be "pointy". More info can be found here