IngeAX,
You are getting conflicting opinions because this is sort of a gray area. The requirements for SPCC are well defined in the Japanese standard JIS G3141. 1008 is a designation from SAE J403, which is for chemical composition only, not product form (sheet, strip, bar). So there is nothing about mechanical properties, tolerances on sheet thickness, etc. In terms of chemical composition, 1008 from SAE J403 is similar to SPCC, but not exact. The C content is limited to 0.10% maximum for 1008, whereas SPCC allows 0.15% max. ASTM standards, not SAE, are used for defining product forms such as sheet. ASTM A1008 is the North American analog to JIS G3141, and has grades that line up well:
JIS ASTM
SPCC --> CS Type B
SPCD --> CS Type A
SPCE --> DS Type A or B
SPCF --> DDS
SPCG --> EDDS