That's like saying Twitter is the same as Google, just because principal founders came from Google.

I'm not really sure how you can read the history of the organization and come up with that. al-Tawid was founded at around the same time as al Qaeda (within a few years), and they merged to become al Qaeda in Iraq and then ISIS/ISIL.

In some ways the person I was responding to was right because, between Osama and al Zarqawi, Osama was definitely the moderate. But you're talking about wanting to kill everyone who isn't a muslim vs. everyone who isn't sunni muslim.

The idea that ISIS is something fundamentally different is driven by the media. It's sort of how DARE tries to scare parents by saying "This generation is smoking some really crazy stuff you're not familiar with!"

Daesh is taking and holding territory. And they're dragging major powers in to fight them there, quite deliberately. That's pretty different to me.

Pretty different from what? Afghanistan in the 70s/80s was almost exactly this: a destabilized national government, insurgent forces taking and holding territory, global powers being dragged into it. The only differences are the rhetoric.

Edit: here, this may be a link that helps you understand more of the history of the region as well as the context for the rise of AQ/ISIL: https://en.wikipedia.org/wiki/Maktab_al-Khidamat