THEN is an adverb relating to time. Depending on its use, it means “at the time” or “afterward.” For example, “We ate breakfast and then we left for school.”
THAN is a conjunction that is used when comparing two or more things. For example, “Chocolate ice cream is better than strawberry ice cream.”
DVDs are more expensive THAN videocassettes.
We ate and THEN we went to the movies.
Both “then” and “time” both have the letter “e” in them, and “than” and “comparison” have the letter “a” in them.
thAn = compArison