Difference between 4 kinds of vcm (SP177, SP177-1,SP177-C,DP177-C1)

Here is the difference among SP177, SP177-1, SP177-C and SP177-C1:

SP177: Ford VCM2 hardware support WIFI, but need to buy the WIFI card
SP177-1: Ford VCM II with WIFI Wireless Support Including all SP177 function and can directly use wifi function, No need purchase additional WIFI card
SP177-C: Ford VCM II Support Wifi, Need customer buy WIFI Card seperately
SP177-C1: Ford VCM II with WIFI Wireless Version includes all SP177-C function, and including wifi card.