however and though have a closely meaning but why

The words though, although, however, have very similar meaning but they are used is different structures. The conjunctions 'although' and 'though' are interchangeable.we use it before a clause. Ex: Although/ though he pass the test, he didn't get the job. we went out although/ though it was raining. However is translational adverb . it goes at the beginning of the sentence. Ex: He pass the test however he didn't the job. However hard she tried,she couldn't do it.