system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are Hezbollah, Al Qaeda and ISIS against each other?
gpt
Firstly, religion.  Al-Qaeda and ISIS are Sunni Arabs, Hezbollah are Shi'a Arab.  Huge ethno-religious conflicts between the two.

As for AQ and ISIS, it's a bit more complicated.  They're not really enemies, they just disagree with each other.  You've probably read in the news that ISIS used to be affiliated with AQ until early this year, when they were kicked out for being "too extreme", which is partly true.

The short version is that ISIS see themselves as a state, rather than a terrorist group.  That's a designation they kind of deserve, to be honest.  They run police forces, local governments, schools, and even post offices in the territory they control.  Befitting their role as a state, ISIS thought that, instead of swearing loyalty to AQ, AQ (as a non-state group), should swear loyalty to them, much as AQ swore loyalty to the Taliban back when they ran Afghanistan.  This caused a big argument (in Islamic culture, a personal oath of loyalty should be to the death), and AQ disaffiliated with ISIS.