That's a good point. Resisting a military occupation through force is, sometimes, arguably a legitimate fight... but then, innocents from both sides are inevitably caught up in the fighting. "Freedom fighter" and "terrorist" are often interchangeable, depending on perspective.

Anti-Marxist fighters in 1980s Central America = 'Terrorists' to many; 'freedom fighters' to those opposed to communism.

Anti-apartheid fighters in 1980s South Africa = 'terrorists' to the South African government of the time, 'freedom fighters' to everyone else in the world.

There are countless other examples, too - the Mujahadeen in Afghanistan, present-day militants in Chechnya... the list goes on.

However, 'fighting for freedom' can't ever justify the slaying of innocents - anyone's innocents - in my opinion.