depends if you have played persona 5.
- more grounded in reality / setting. The plot of Persona 5 is ridiculous, it may be really like that in some instances in Japan, but I found most scenarios and what happens to the characters completely unrealistic and more like Fantasy on how a kid or teenager sees the world.
- The cast of P4G has more character and feels more believable.
- combat in P4G feels more relaxed where you don't need to stress about exploring 100% of the dungeon because it is random. Especially P5R has vastly expanded the dungeon exploring with missable chests, etc.
P5R is more polished and has vastly more things to do in your free time, one of the things it gets criticized because of padding.