From the Canonical List of Commodore Equipment

First column is the variation, 2nd column is the variation differences via the codes in the top paragraph and if there is a third column it means it has been confirmed by someone who owns one.
AlanD


Code:
VIC-20 Series:  22*23 screen, 5kB RAM,  Basic 2.0, one piece. 
                Could be hooked to TV with RF modulator.
                Cream (C), or Off-White (O) case.
                Flat top keys with Square type font on keycaps (S), 
                Indent top keys with somewhat square font and thin letters 
                for RESTORE/CLR/HOME/INST... (I), or
                Indent top keys with rounded type font (R).
                2 Prong PS adaptor (2) or DIN PS adaptor (D).
                Black/Silver Decals (B), or Brown/Color Decals (H). 
                5 pin video connector (5), or 8 pin video connector (8) 
                "2" implies VIC-20 motherboard.  "D" implies VIC-20CR 
                motherboard.          
* VIC-20 1      SOB2                                                          
* VIC-20 2      ICHD                                                          
* VIC-20 3      ROB2                                                          
* VIC-20 4      RCHD8                                                       JB 
* VIC-20 5      SCHD                                                        JB 
* VIC-20 6      VIC with 2001K Keyboard.                                    MS 
* VIC-20 7      RCBD5                                                       SD 
* VIC-20 8      CS2B5                                                       RN 
* VIC-20 9      CI2B5                                                       RN 
* VIC-20 10     CIH25                                                       BZ 
* VIC-20 11     ROBD5                                                       BZ 
* VIC-20 12     RCHD5                                                       MG 
* VIC-10        Japanese VIC with 2001K keyboard.        
* VIC-1001      VIC-10? Japanese VIC with both chars printed on keys.       TG 
* VC-20 1       SCHD5 (German) (source says has beige instead of grey? case) 
* VC-20 2       RCHD5 (German)                                              MH 
* VC-20 3       R5OB2 (German) Color VIC logo...                            CE 
* VC-20 4       HD (cheap label) (German)                                   RC 
* VC-20 5       HD (better aluminum label) (German)                         RC 
* VC-20 6       2 (UK)                                                      RC 
  Gold VIC      Commemorating the 1 millionth VIC-20 made in the U.S.
* Silver VIC    Commemorating the 2 millionth VIC-20 made in the U.S.