However means : nevertheless; yet; on the other hand; in spite of that: We have not yet won; however, we shall keep trying.
Even though means : 1. (used in introducing a subordinate clause, which is often marked by ellipsis) notwithstanding that; in spite of the fact that; although: Though he tried very hard, he failed the course. 2. even if; granting that (often prec. by even ). - adverb 3. for all that; however.