The difference, imo, is that XIV is built around being tard-friendly for the bulk of its content, with a low skill floor. WoW, conversely, has a higher skill floor (not much, mind, but I would argue that it's reflected with things like a faster GCD and different mechanics to keep in mind and learn without really being taught it, etc.) that ratchets up more and more. You have to really be going out of your way to be a net drain on your group and even then, you should be able to clear most content. A freestyling SAM or a Blizzard Mage can still clear content if the rest of the group aren't mouthbreathers.
Once you start dipping your toe into later expansion content (and higher levels of difficulty) you start seeing problems crop up where one person who doesn't know a fight can basically waste your time.
Anyone who has prior MMO experience shouldn't have any problems. But I find XIV's community is comprised of MMO fans and JRPG fans/MMO first timers. The latter category is a not inconsequential amount of players and it's amusing seeing it reflected with folks being utter dogshite at PVP or with like the Ivalice raids (which aren't particularly difficult but have a few curveballs mixed in.) Very similar to early WoW with EQ vets and folks who were picking up WoW cos it was either a Blizzard product or was the hot new thing at the time.
The average XIV player has a much higher skill lever than an average WoW player, although you can chalk that up to any factor of your choosing.
- XIV forces players to engage in group content constantly - which means even the most anti-social players will have to engage with core mechanics (bosses, Area of Effect skills, all of the various effect markers). WoW has one forced dungeon that doesn't require any roles and reinforces 0 mechanics.
- XIV has dungeon mechanics
outside of dungeons - even to some degree on normal mobs. Even if you're actively avoiding dungeons, you're still being forced to engage with the core mechanics of the game. FATE bosses (which are plentiful in every zone) have a full suite of dungeon/boss mechanics. WoW mobs in the world mostly simply stand still and auto attack - and the only mechanic players can practice on them are CC skills (if you pull too many) and interrupts (if they have spells that can be interrupted, and you are a class that can interrupt). Very few mobs in WoW do anything but auto attack (and most of them were added in Exile's reach).
- XIV classes/jobs at a low level play similar to the class at a high level. Each skill is introduced every few levels and builds onto the design at max level. WoW classes at low levels feel pretty different than at high levels (missing skills, abilities, rotations, etc)
- XIV also forces players through Class/Job quests, which function as job specific tutorials for players. (With the WHM one being the funniest - it being a fight about "You can't just sit and heal, you're going to have to fight stuff you fucking coward").
- XIV has a much tighter class design (and substantially less classes) so there's less variation in how the roles are played inside of one another. In XIV anyone who plays Warrior can play any other tank class with only a small adjustment. In WoW, Guardian Druids and Protection Warriors have drastically different toolsets/abilities/gearing/etc.
- XIV has very little RNG inside of it's class designs and has detailed rotations that make sense and have a basic flow and are easy to explain and understand. WoW has a lot more RNG in it's class design which is built on top of several layers of borrowed power (tier set bonuses, heart of azeroth, whatever shadowlands did, glyphs, legendary abilities) and clunky mechanics that are never explained in any detail.
- XIV doesn't have "I don't know what the fuck do to with these classes" classes, unlike Ret Pally, Survival Hunter, and any PVP spec.
- XIV has a longer GCD which means you've got more time to decide your next move, but dropping a combo/making a mistake can be
massive. WoW can be played by most classes with ~80% effiency by open palm slapping the keyboard (to a point where the WoW Dev team had to get rid of the /castrandom macro for that exact reason) because mistakes don't size up all that well.
- XIV has a much cleaner UI/UX than WoW. When you make a mistake in XIV that you aren't supposed to (ex - hit with an avoidable mechanic), you are marked with some kind of indicator (usually a Vuln Stack) to let you know "you can avoid this". WoW has no clear indicator of "avoidable damage" or "unavoidable damage". There are WoW mods that try and track this for you, but they're not even partially good at it.
- XIV has a cleaner raid design and "what is going on" and "what am I supposed to do" are extremely readable where as WoW players are forced to half rely on Deadly Boss Mods (or similar).
- WoW has constantly shifting and changing abilities, which mean each raid is extremely dependent on Raid Composition and the current patch (Example - Death Knight's Anti-Magic spells negating entire mechanics in raids). XIV has much less "bring <class> to skip mechanics".
- A FFXIV party is 4 people (tank, heal, dps, dps) and a FFXIV Raid is 8 people (2 tanks, 2 heals, 4 dps - or two parties merged together). A WoW dungeon is 5 people (tank, heal, 3 dps) but a WoW Mythic raid is 20 people, but is 1/2 tanks, 3-6 healers, and the rest dps - not a simple party merge. On top of that - WoW also has design issues with not making ranged DPS better than Melee DPS so there's a huge swathe of classes that get left out. A WoW raid can often be "the minimum classes we need and then 10 copies of the best/class spec possible at the moment"
- XIV doesn't have any kind of castable/trackable buffs. You don't
have to bring 3 paladins for 3 blessings, a druid for BOTW, a mage/shaman for Bloodlust, etc.
- XIV has a built in threat meter, where was WoW doesn't (or at least didn't when I still played).
- XIV has no "random" resource management - unlike Rage, Energy, or some classes MP bars.
- XIV gear doesn't change a classes playstyle, where was WoW's drastically changes at certain patches, thresholds, tier sets, leggos, etc. It is less severe now than it was then (with Expertise and Hit Rating gone) but it's still drastic.
- XIV doesn't have grinds or timegates to get into content - meaning that the average XIV player is more likely to engage with it. In XIV, you can raid really easily because there's no "pre-raid" prep needed/treadmill/rep requirement.
I'm not saying that people who play XIV are big brained and WoW players are small brained - but if you took the same person and made them play both games at the same time, they'd become better at XIV much more naturally and easily.
My experience in both games is that in XIV I feel comfortable pugging in Savage (aka Mythic) raids but in WoW it was extremely common to have trouble in the LFR versions of raids.
Personally, I have played several classes in WoW and points where even in a high end raid - I was pushing 3 buttons and doing top DPS (DK, Warrior, Rogue, and Hunter). There were points in raids when healing (Paladin, Priest, Druid) where I was able to just spam AoE heals and keep everyone up.
I've never been able to phone it in nearly as much in XIV and I've never seen anyone be able to either.
