She has white mage for support while Mediena does not. Salire's has slightly better resistance to slash, pierce, missile, and blunt since Mediena's resistance are -20% flat. Salire's mastery ability is twice as better than Mediena.
Salire has the capabilities with Holy to 🔥 dodge built teams while still offering strong support and damage to her team. Tmr can be solid choice to run and is comparable damage to Mediena. Her ai also behaves with a much better order of choices and especially when subbed whm. She will stay back and use protect and shell and actually used tmrs.
I have Medi on my ios device and I have Salire on the Android. Salire is better at 99 than Medi. White mage sub job is better than Medi's sub jobs. Also her white mage abilities use TP and her BM abilities use AP. Medi's best sub job is Ninja which also uses AP so she's losing it faster. And she is squishier.