One big difference is the addition of a new four-model structure with Tour (T) Players (P) Extreme Forgiveness (XF) and Super Game Improvement (SGI) now offered. But the real design difference has to do with the a new material used in the clubs that produces more speed and distance among other things.
The new RTX 4 also differs from the previous RTX 3 by offering less offset a more compact profile and four new sole grinds all of which were designed via significant input from Cleveland Tour staff members like Keegan Bradley Graeme McDowell and Shane Lowry.
The LO is the most compact model with a low and forward CG location that promotes a low-mid trajectory. It’s the most iron-like design of the group and is most likely to work for those with faster clubhead speeds.