Is being an Executive Assistant more challenging than a Virtual Assistant?

They're pretty much the same. VA is the general term. EA is just specific to those working exclusively for a person in the top management. Your workload all really depends on your client, so can't really compare. But usually, if you're an EA, you should easily adapt to a fast pace working environment since you'll be the first point of contact to get thru the boss. So one should excel in management, coordination and multitasking.