A rule of thumb for discerning between a tank and a fighter
Below are some characteristics that tanks and fighters have. Of course, not all tanks/fighters have these traits, but like in the title, a rule of thumb. When I say "ability," I'm including passive.
Tanks 3 crowd control abilities, at least one (and often two) of which is a hard CC. 1-2 reliable crowd control (instant cast, large hitbox, targeted ability, etc.) 1 ability that grant durability (heals, shields, %damage reduction, armor/magic resist steroid) 1 dash ability with crowd control attached Armor/Magic resist scaling (rare)
Fighters Enhanced autoattacks (often also AA resets) 0-2 abilities with soft CC 0-1 hard CC, often single target, has small hitbox, conditional, etc. (hard to land, or short) 1 damage steroid In combat healing (through lifesteal or similar effect)