I am fine with the basics (e.g. classical vs rock/punk vs pop based on instruments) but there’s loads of other terms that aren’t very intuitive.
What is the difference between “alternate” rock and I guess “regular” rock? What is the difference between rock and punk? What is post-(insert subgenre here, like punk)? What is pop rock (the music subgenre, not the fizzy candy rocks), and how is it different from rock pop? What makes music “progressive”? What on earth are the “blues”? What is the difference between rock, metal, hard metal, heavy metal, etc. aside from an increasing level of angriness and decreasing level of clarity? etc etc
All that really matters to me is where they put them in the record shops that I tend to visit, so that I can find what I want, or similar stuff. This can vary shop by shop though - but usually not too much. If in doubt just ask the shopkeeper.
If the shop didn’t have enough stuff to warrant a subdivision, then the term doesn’t matter. If you’ve started using more specialist shops, then it may start to matter.
If you’re trying to understand music ‘journalism’ / marketing/PR bullshit instead of listen to music then I have no advice. I’d rather spend more time listening to some music/radio or just randomly going to concerts than reading 90% of the shite that people write about music.
The only real issue comes for very new groups where they don’t even have a bandcamp to listen to or any half decently recorded youtubes. In those cases I’d expect ticket price to be just a few quid, so just risk it and go to the show. You can always leave if it’s unbearably shite.
If you want to get an idea about a genre , try to pick up a cheap compilation or samplers, or find a radio show that might play it.