Vodka has no effect

A friend of mine seems to have highly variable reactions to different types of alcohol. I’ve read online that all alcohol is the same and has the same effect on you and that how you feel under its influence is purely psychological. She can drink an impressive amount of vodka like it’s water and be completely fine for example. However, she can’t touch cider, a few drinks and she’s way more drunk than I’ll see her after drinking anything else. How does this work?