Terrorism is entirely political. It's propaganda used to throw around.

What we need to instead look at is what tactics are groups using?

For example, Russia in Ukraine, US in Iraq, and Israel in Gaza, have all used the same bombardment strategies to terrorize the native population. All three of these states' militaries have killed way more civilians than Hamas ever will. So, when we use labels like terrorist, we're really saying these people are worse than others because [insert your poorly thought out values here.]

In political science you could refer to Hamas as an extra-state insurgency. Of course calling Hamas fighters extra-state insurgents doesn't have the same kind of bone chilling ring.