Maybe yes, and maybe no on the Expedition and the Discovery having the same chassis. True they may both be made by Freightliner, but in the 2000-2001 series, some Expeditions did not have the air suspension system, they had conventional springs.
I sat next to a fellow with a 2000 or 2001 Expedition a few years ago, and got an ear full from him.
I think that if you check, you will find that the Discovery has a 'bigger bang for the buck' than the Expedition, especially in those year series.
Be advised that in the Discovery, prior to the 2002 series, they have a 30A system with a EMS. The 2002 series, and later have a 50A system with EMS. I am not sure about the Expeditions for those years series, but I think they also had the 30A system, which were often overloaded when trying to run too many appliances/air conditioning. The main problems seemed to be a 'hokie' 30A circuit breaker in the power entrance compartment, and a 'too light' 30A ATS relay setup. I have assisted in repairing a couple of them on the Discoveries, and was thankful for our 50A setup. Again, not sure about the Expeditions for those years.
Also, starting with the 2001.5 Discovery, they came with a 330HP CAT engine, and a "flat floor" living room slideout. Prior to that model, they came with either the 275 or 300 HP Cummings power plants, if memory serves me right.
While I am not bad-mouthing the Expedition, as I think it is a fine unit, I personally think the Discovery has more to offer.
One Giant Plus for the Discovery is the Discovery Owners Association, INC.
which has over 1200 members, who have a wealth of information on the Discoveries.
So, IMHO, my recommendation would be a Discovery in a 2002 or later version.
2002 Discovery 37T 330 CAT