Northrup built both planes roughly 40 years apart. The first YB-49 was rolled out in 1947, and the first B-2 was rolled out in 1989.

From this source on the YB-49:

Span: 172 ft. 0 in.
Length: 53 ft. 1 in.
Height: 15 ft. 2 in.
Weight: approximately 213,500 lbs. (maximum alternate weight)

Armament: Designed for bomb loads up to 16,000 lbs. of bombs

Engines: Eight Allison J35-A-5 axial flow turbojet engines of 4,000 lbs. thrust each maximum.

Crew: 6 (pilot, copilot, flight engineer, radio operator, bombardier, gunner). There were provisions for a relief crew and two more gunners on the proposed production version.

From this source on the B-2 (edited for length):

Power Plant/Manufacturer: Four General Electric F-118-GE-100 engines
Thrust: 17,300 pounds each engine (7,847 kilograms)
Length: 69 feet (20.9 meters)
Height: 17 feet (5.1 meters)
Wingspan: 172 feet (52.12 meters)
Speed: High subsonic
Ceiling: 50,000 feet (15,152 meters)
Takeoff Weight (Typical): 336,500 pounds (152,635 kilograms)
Range: Intercontinental, unrefueled

Besides the interesting fact that both planes have exactly the same wingspan, the B-2 almost certainly has more wing area than the YB-49. That would allow it to lift the heavier weight (the B-2 is about 123,000 pounds heavier). Also helping is the fact that the B-2 has a combined total of 69,200 pounds of thrust verses 32,000 pounds for the YB-49. Those 4 bigger engines on the B-2 probably have a significantly lower fuel consumption than those 1947 turbojets.

The B-2's aerodynamics are better, the engines are better, the avionics are vastly superior, it's faster, has longer range, carries a heavier bomb load, and only needs a crew of two. Gee, 40 years did result in some improvements after all - without the need for anti-gravity devices or other delusions.