What is the difference between "aunque + indicative" and "aunque + subjunctive"?

"Aunque" has two meanings : "even if" and "even though".
"Aunque + indicative" :When using "even though", the fact is already known but maybe not by the listener.(e.g.: Even though I am lactose intolerant, I sometimes drink milk. => Aunque soy intolerante a la lactosa, a veces bebo leche."Aunque + subjunctive" :When using "even if", the outcome is not known.(e.g. : Even if you don't surf, you can come and watch the surfers ==> Aunque no surfees, puede mirar los surfistos.