I do NOT claim to be an adequate grammarian, nor do I want to become the
Grammar Police. However, I do tend to get a little wound up when self
proclaimed pundits wax prosaic and show their ignorance by confusing two
of the words in the title of this rant.

Provided below for their edification and enlightenment are dictionary
definitions (used without permission) and sample usages, in italics, of both.

Non-native English speakers may be forgiven, but should still work on it.

THAN
-conjunction

1. (used, as after comparative adjectives and adverbs, to introduce the second
member of an unequal comparison):
She's taller than I am.

2. (used after some adverbs and adjectives expressing choice or diversity,
such as other, otherwise, else, anywhere, or different, to introduce an
alternative or denote a difference in kind, place, style, identity, etc.):
I had no choice other than that.
You won't find such freedom anywhere else than in this country.

3. (used to introduce the rejected choice in expressions of preference):
I'd rather walk than drive there.

4. except; other than:
We had no choice than to return home.

5. when: We had barely arrived than we had to leave again.

–preposition
6. in relation to; by comparison with (usually fol. by a pronoun in the
objective case):
He is a person than whom I can imagine no one more courteous.


THEN
–adverb

1. at that time: Prices were lower then.

2. immediately or soon afterward: The rain stopped and then started again.

3. next in order of time: We ate, then we started home.

4. at the same time: At first the water seemed blue, then gray.

5. next in order of place:
Standing beside Charlie is my uncle, then my cousin, then my brother.

6. in addition; besides; also: I love my job, and then it pays so well.

7. in that case; as a consequence; in those circumstances:
If you're sick, then you should stay in bed.

8. since that is so; as it appears; therefore:
You have, then, found the mistake? You are leaving tonight then.

–adjective
9. being; being such; existing or being at the time indicated:
the then prime minister.

–noun
10. that time:
We have not been back since then.
Till then, farewell.