Then - Than.

There are several contexts in which the terms are used, but generally speaking you use "than" when you're comparing or contrasting things:

"_____ is bigger than _____."
"I'd rather _____ than _____."
"It's better to _____ than to _____."



You use "then" when you're making an "if" statement or narrating a sequence of events:

"If ______ happens, then I'm going to _____."
"First I told her _____; then she did _____."
"I finish work at 5:00pm. I'll see you then."

you should google the words or look them up so you get all the various definitions and examples... we could go on forever supplying examples here and still miss a few.

Mame--

A lot of our English questions come from foreign students. Some of them have teachers for whom English is a second language.

While I adore the English language, I'm not going to call it "logical".

Google is a wonderful invention--but you have to be fairly literate in English to Google in English.