Endurance 4.0
1:00:00 51 TSS 0.72 IF
Endurance parts are 70% FTP, 3 sprints at 180%
Endurance 4.2
1:00:00 44 TSS 0.66 IF
Endurance parts are 65% FTP, 2 sprints at 180%
Whatever AI machine learning model assigned the difficulty to those 2 workouts…should probably be double-checked 
the second workout is easier in every possible way yet rated higher.
There’s been a few times I’ve encountered this when looking at alternate workouts.
The only thing I can see is Mokulumme is 43 minutes at 65 and Cheaha is 42 minutes at 70. Since the sprints are probably ignored in the calculation that 1 minute must be heavily weighted. Either that or the fact that the steady state on Mokulumme is longer. One interval of 20 and one interval of 15, whereas cheaha is 20, 8 and 8. That sprint in between definitely makes it harder, but I’m supposing that is ignored because it’s not endurance.
Sorry for the confusion, Cheaha’s workout level was incorrect, but has been fixed and is now showing as intended: an Endurance 4.3 workout. Thank you for letting us know!