sweet....i've heard these are actually M250R's and the M250 is a M400 Type Housing with a 250 W Lamp and Polycarbo Refractor?

You're right its the M250R but by habit I call it the M250. When I think of the M250R I think of the 70s-mid 80s model. The '77 GE catalog called it the M250R also.

Although its not official, it could clarify this way:
Original M400: M400R
Split door M400: M400R1
Single door, officially called the M400R2
Current fixture M400: M400R3

Describes the generations clearly.