IMO the GBC isn’t really a full successor to the original game boy. Even though there were exclusives the actual system is more or less just an overclock/spec bump from the original game boy. Nothing about the system (architecture, input layout, developer experience, etc.) fundamentally changed Edit: aside from the PPU being able to handle colors on the screen.
On the other hand, the GBA is a different generation because it has a completely different architecture and development process. In order to maintain backwards compatibility, Nintendo basically just stuffed the original GB/GBC internals into the GBA alongside the GBA hardware, and it will just decide which CPU to use depending on the cartridge it has loaded.
IMO the GBC isn’t really a full successor to the original game boy. Even though there were exclusives the actual system is more or less just an overclock/spec bump from the original game boy. Nothing about the system (architecture, input layout, developer experience, etc.) fundamentally changed Edit: aside from the PPU being able to handle colors on the screen.
On the other hand, the GBA is a different generation because it has a completely different architecture and development process. In order to maintain backwards compatibility, Nintendo basically just stuffed the original GB/GBC internals into the GBA alongside the GBA hardware, and it will just decide which CPU to use depending on the cartridge it has loaded.