Is steel lighter than iron?

I know that steel is generally iron with carbon and probably some other things in it, but I'm doing a research paper on architecture in Tokyo, and touching on the Tokyo Tower.

The Tokyo work is larger than the Eiffel Tower by 12 meters, but lighter by 3000 tons. The only reason I can find for the difference in weight is that the Tokyo Tower is made of steel and the Eiffel Tower in made of iron, and since the Tokyo Tower is modeled after the Eiffel, there's really not a substantial difference in the amount of metal used....
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