The Answer You're Looking For
Haswell and Broadwell are generations within the Haswell architecture.
Skylake, Kaby Lake, Coffee Lake and Cannonlake are generations within the Skylake architecture.
Icelake and Tiger Lake are generations within the Icelake architecture.
So yes, both the 8th and 9th Gen can be Icelake, but one will also be Tiger Lake.
Lake is one of those words that looks weird when you see it repeated lots.
You're welcome.