What I mean is that the C64 only came with one CPU type, one sound chip type, one configuration of memory, etc. There was no variations coming from the factory. Once people got there hands on it however...
The Amiga/Atari ST *family* might have sold more but the catch is that the C64 was not configurable. All the C64 came with one configuration (then eventually the C64C came along) and that's where the trick is.