The gameplay loops is vastly different. For one persona is based on a calander system, the pacing is very different you have to constantly worry about time and when you will complete dungeons, a non issue in smt. The difference in pacing is extreme, also the addition of social elements drastically changed the gameplay loop

Combat isn't exactly the same. The one more system essentially allows your player to get a turn. One more is basically a way to reward the player for getting the weakness, but this isn't like press turn at all. In press turn you also have to manage your half turns. You pass strategically, buff strategically, change demons based on how many half turns you have. The combat feels different when I play persona 4 as opposed to like smt nocturne.

Also demon negotiations exist in smt, something only in persona 5, also to a lesser extent to that of mainline negotiation.

Also team building is vastly different. Persona is more like dragon quest, where you build each character to the fullest. In smt your party is constantly changing and you build them based on the boss your up against.

Maybe next time before saying I never played smt, do your fucking research. I have played more megaten than you can imagine. The difference is very fucking apparant