How the conjunctions 'even though' and 'even if' differ

A FILIPINA writer based in the Middle East requested me in mid-2017 for a refresher on the difference between "even though" and "even if." I don't recall having discussed the subject in this column nor in Jose Carillo's English Forum over the years, but I had noticed that some writers — even professional ones — tend to use those two contrastive conjunctions interchangeably. I was therefore glad that the writer, Forum member Miss Mae, asked me to clarify their proper usage.

To begin with, I'd like to emphasize that as a rule, "even though" and "even if" are not interchangeable. "Even though" is used to express a fact or something that's real or true, while "even if" is used in a supposition or for something imagined or unreal.