How much taller is the building Burj Dubai than the Empire State Building?

Much taller, by any standard. But the names of both have changed:

Burj Dubai is now Burj Khalifa, the tallest building in the world at 2717 feet (828 m).

Sears Tower is now Willis Tower, the 2nd tallest building in the US at 1451 feet (452 m).

This is more than 87% taller. If Willis were 100 feet shorter, Khalifa would be twice as tall.

There is a bit less difference if you measure to the habitable height:

It is 1918 feet to the 163rd floor of the Khalifa vs. 1354 feet to the top floor of the Willis Tower. This is still half-again as tall as the Chicago skyscraper's usable height.

The Willis Tower, because it is not as drastically tapered, has about 25% more floor space (4.4. million vs 3.3 million square feet) than the Burj Khalifa.