The top of the line i9-8950HK and the Xeon E-2186M feature six cores/twelve threads that can reach boost clocks of 4.8 GHz. The mid-range i7-8850H and Xeon E-2176M feature the same core/thread count, but can boost only to 4.3 - 4.4 GHz. Finally, the entry-level i5-8400H and i5-8300H come with 4 core and 8 threads that can go up to 4.2 - 4.0 GHz.
https://www.notebookcheck.net/Intel-Coffee-Lake-H-Mobility-CPU-lineup-specs-get-leaked.279670.0.html