As vs. Though

As and Though are two conjunctions that can be used after adjectives or adverbs meaning Although:

- Unlikely as /though It might seem ,I'm tired too.
- Hard as/though she worked, she failed in his exam.
- Tired as/though I was ,I took her to the station.

They can indicate an emphatic contrast.
As comes with much ,but not though.In this use,it is used in sentence initial position and doesn't come with adjective or adverb.

- Much as /though he seemed to be hungry , he didn't eat so much.
- We went on a one week trip last week,as much/though we were busy.

As in this structure can be used to mean because:

- The horrible as the movie was, the people under 16 were not allowed to watch it.
- The rich as he was, he could afford the luxury cruise ship.

Although and Though can be used alone with adverbs and immediately after them.

- The marriage ,although/though brief,was a happy one.
- The doctor ,although/though experienced, could not diagnosis her cancer.
- Although/Though shy, she took part in many parties.

Though can be used in the middle of a sentence between two clauses to mean although.

- It might be worth your while to go to the court,though,and you 'll need expert advice.
- I enjoyed the movie,though I thought it was too long.

Though can also be used at the end of the sentence as an adverb meaning however,nevertheless.

- It's a hard work.I enjoy it though.
- He speaks many languages. He does know Spanish,though.