Headphones

Hello! I was looking through the sidebar's list of recommended earphones, and after clicking through some of them, I've realized that I actually don't know if that's a list for me, a consumer looking for something to jack into my phone.

I've tried quickly looking for differences between IEMs and headphones, but didn't managed to reach a conclusion. I've vaguely familiar with the term "monitors", since I do help out from time with band shows, but I never actually dealt with audio equipment or audio setup (aside from carrying it to the stage). From what I assume based on what I've seen, monitors are the the speakers that play on stage, so the band can hear what they play. And IEMs are earbud versions of monitors that the band uses instead.

I've always assumed that they are basically headphones/earphones, just connected to some kind of transmitter, and calling them IEMs just makes it easier to find earbuds focused on audio quality, because the term is not as mass-marketed as earbuds are. But judging by the cable connector I've seen on some of the IEMs I've looked at, it's probably not a jack.

So, what are the differences? Is it a different tech all-together, or are they really just a higher quality earphones with better connector? Would looking for IEMs instead of earbuds make it easier to find better earbuds for regular use, or are they meant only for studios and I'll have a hard time even connecting them without aditionall equipment?

Thank you for any reply or explanation. I realize this question may seem pretty basic, and I hope it's not too out of place - I have almost zero experience with audio, but I did start recently DJing (where all I needed so far was to be able to connect RCA into a mixer) and helping out with setting up band shows, so I'm asking this question not because I'm shopping for earbuds, but because I'm honestly interested in learning something new about how different tech around music work and what's the common language around it.