Even though is used to introduce a condition which currently is true, so both sides of the statements are facts: FACT even though FACT
Even if = introduces a hypothetical condition that is not yet true, so the first statement is true, but the second statement you are not sure about or it hasn't happened yet.: FACT even if NOT YET TRUE
たとえば: I will go to work even though I'm tired. (仕事に行く。そうして、疲れた。二つのは本当・じったいです。You are going to work and you are tired. Both are facts.)
vs. I will go to work even if I'm tired (仕事に行く。でも、疲れるのことが分からない。You are going to work, but you are not sure if you will be tired.)