Hiroshima and Nagasaki vs. Chernobyl

Both these places were affected by nuclear radiation, but while the Japanese cities have thrived, Chernobyl remains a wasteland for many years to come. This is because of two main reasons:

1. The atomic bombs dropped on the cities only contained ~14 pounds of plutonium/uranium. The nuclear reactor in Chernobyl however, contained nearly 200 tons of uranium.
2. The bombs exploded in the air over a wider area, which helped dissipate the radioactive particles. The explosion of the Chernobyl reactor was directly on the ground, and much more concentrated.

This also applies to the nuclear disaster in Fukushima.