Well as you're switching from FFXI to FFXIV, I feel an overall high level list of stuff/FAQ like this might be appropiate here, rather than go through wiki/forum/site:
- There is no skill ups in FFXIV, and each class is restricted to 1 weapon
- Changing your main weapon, providing you've unlocked or have a class high enough to equip it, will change your class.
- Class = base class you start out with, at level 30 you can quest for your job stone which when equipped upgrades your class to a job (gladiator > paladin); although you become a PLD, you continue to accumulate EXP on Gladiator, the PLD's level is determined by your Gladiator level
- [GAMEPLAY] With the exception of healer classes, BRD, SMN and maybe BLM, kinda, each class has a sequence moves called a rotation they must do to maximise DPS; you can do them out of order, but the game won't recognise them as combos, and therefore you do the base/default damage rather than the combo "bonus" damage
- TP in this game is more or less a energy bar, physical classes use TP for their abilities, mage classes use MP
- Every class has a built in "flee" button (called Sprint) which costs all your TP. This increases movement speed for up to 20 seconds at full TP, and is on a 30s cooldown
- TP is recovered at 60-80 something odd per tic in battle, 100/tic outside of battle
- Combining these facts, it is important not to flee and then decide to engage in battle, as you might start off with only 200 odd TP and be forced to cool off a tiny bit before pushing buttons. Although TP charges up in no time outside of battle, you might sometimes be forced into one shortly after hitting flee
- Aside from dungeon (instance) enemies, everything will leash once you run out of their immediate radius.
- As a result, you can probably run a low level char through high level areas without much consequence; the environment does not feel dangerous [did you shit yourself running through valkrum dunes and into that tunnel to get to your EXP party for the first time? You won't feel like there, or anywhere]
- No stealth in this game, although the 2 (3?) gathering classes do have such a move, but those classes can't battle either, so ...
- No NMs/camping, although there are "sudden" events called FATES which usually drops a NM in the area for everyone to fight, or a horde of mobs. Anyone who participates gets EXP/gold/tokens. These happen extremely frequently and every zone has multiple FATEs. They do not drop anything.
- All mobs aside from the FATE NMs can be soloed; some NMs can be soloed if you can self sustain yourself
- At level cap [50], a level 48 mob will not kick your ass, you will kick its ass unlike FFXI where even a level 60s mob can be a threat to a level 75 (fuck you level 60s undead!!!!)
- Downtime is none existant, once out of battle you recover HP MP TP rapidly
- The game will auto level sync you for all instances/FATES to be level appropiate. This means friends can help you on stuff without much sacrifice/need for level appropiate equip
- No moon phase, face direction for HQ, clock related events (that I know of), shitty Kirin-like doors, team doors, or any dick gimmick from FFXI
- Next to no gear swaps; you can't swap gear in battle. Some people have slightly situational builds for their classes (i.e. WARs carry DPS accessories), but you can 99% most likely function without these specialise builds
- The Materia system in this game is somewhat similar to the Synergy Armor in FFXI where you can attribute the gear with some extra stats. Unfortunately it's not FF7, so don't jump thinking that
- You'll see many familiar FFXI names/models; a nice nostalgic lick in the face
- The loot system in this game has 3 buttons:
Need (priority 1)
Greed (priority 2)
Pass (pass)
If the gear is appropiate for your class, Need will be available/lit up for use. That way you only compete with other people who meet the same requirements for said gear. All other classes can only greed. If 1 person uses need and 3 others use greed, you win the gear. If 2 people use need, you compete with 1 other guy for the roll, the other 2 don't get a chance. If no one can wear it at the time of dropping, you can all greed and you'll roll against 4 other people.
- At level 20/30 or somewhere near that, you can pick a NPC Faction (out of 3) to align yourself with. Aside from the distinct look in gear (faction uniforms) available and some stat variations, there is no recommendation other than how you may want to look like in-game
- At level 20/30 (same time as you join a company) you get given a chocobo, unlimited use, no need to feed it etc, and you can also summon it as a 2nd party member (think of it like a NPC fellow) to help fight solo; note that you can't summon your chicken in instances or anything that matters currently. The company you join will determine the costumes available for the chocobo
Can't think of any off-notes an ex-FFXI player might want, but this should be a good start. Feel free to pick it apart or ask more on it.