Section 3 of the 18th and 21st Amendments differ in the use of only a single word. Can you find it? Just kidding. The 18th stipulates that it is ratified by state legislatures, while the the 21st will be ratified by state conventions.

What's the difference?

Typically, a Constitutional amendment is ratified by a state's legislature. In fact, the 21st Amendment is the oddball, the only time a ratification-by-convention process was employed. The idea was to put the change more directly in the hands of the citizens rather than the politicians of the state governments, who might be more beholden to "dry" lobbyists for their re-elections.

Regardless, it worked, and the 21st Amendment was ratified much more quickly than the one it repealed.