Most of the Order and Destruction classes echo each other. The Rune Priest and Zealot are pretty clearly the same class with different coats of paint. Take a Bright Wizard, substitute “dark magic” for pyromania, and you have a Sorceress.
Other classes are clearly the same but sure feel a lot different. Take the Engineer and the Magus. You get it when I tell you that the turrets and the summoned demons are the same; the graphics are different, but you see how a “flamer demon” and a “flame turret” line up. Except that the flamer demons lines up with the grenade turret, and we’re just getting started.
My Engineer throws Acid Bomb: they burn and take away your Corporeal resistance. “Glean Magic” is a soul drain, doing exactly the same thing with Spirit damage and resistance, but getting your spirit sucked by a demon summoner seems a fair ways from an acid burst. You get the same switch between a Sticky Bomb and infecting the enemy with a Seed of Chaos: either way, boom. Does Surge of Insanity feel like a Flashbang Grenade?
The Greenskin and High Elf classes tend to mirror each other, but no one is mistaking a Swordmaster for a Black Orc, a White Lion for a Squig Herder, or an Archmage for a Shaman. Well, until the last two pull out their death rays, then they start to look a bit alike.