Both of the from todays PoV somewhat mind-boggling phrases meant very much in mid 70ties.
The fourth generation bit probably refers to some combination of being real CPU with (somewhat famously) "almost parallel" ALU, requiring minimal external support circuitry and not requiring multiple power supplies with complex sequencing requirements.
And 208bits was quite relevant, because for the time it is somewhat large amount of flipflops/SRAM. For context: 16kbit DRAM chips were first introduced in the same year as Z80.
The fourth generation bit probably refers to some combination of being real CPU with (somewhat famously) "almost parallel" ALU, requiring minimal external support circuitry and not requiring multiple power supplies with complex sequencing requirements.
And 208bits was quite relevant, because for the time it is somewhat large amount of flipflops/SRAM. For context: 16kbit DRAM chips were first introduced in the same year as Z80.