Depends on what aspect of each game you’re referring. My 12 year old nephew just started playing retail so I created a new character to play with him. I’m not using any heirlooms since I don’t want to get ahead of his character’s level, nor am I using auction house greens or blues. Even without heirlooms, in regular white starter gear, my priest’s health only dips a little if we pull a massive group of mobs, like 4-5 or more. And my mana pool never budges at all.
That’s a very different and much easier experience than starting a brand new priest in classic where you very much do need to pay attention to how many mobs you pull because you’ll definitely notice both health and mana decreasing drastically if you’re not careful.