Grace has:

• Recommended 1st person view for maximum horror experience, but you can play it 3rd person. Think RE7 and 8.
• RE2R inventory system (start with 8 slots, expand to 16)
• Tight item management (Personally I just run back and forth to chest and hoard everything)
• Stalker-type archetype (Nemesis, Mr. X etc) that's only scary by the first time because later on the game always throws just right resources to craft items that allow you to stun/one-shot the stalker and make it retreat.
• Her first segment is your classical mansion-type area with central hub > west wing > east wing exploration where you explore the entire area to grab 3 gizmos to open the main door in the hub area.

Leon has:

• Recommended 3rd person view for action gameplay.
• RE4/8 inventory system (suitcase than can be expanded)
• No real item management, you collect ton of items and you shoot away with reckless abandon.
• His first real segment is sort-of open world (feels more like a wide corridor really) where you progress to area 1 > 2 > 3 to get the key items and in the meantime you get another key item that allows you to backtrack to previous areas and unlock previous locked segments for extra loot
• Shop system where you buy/upgrade weapon with points you get for killing enemies. Spares you the trouble of looting peseta.

Playing on casual and done about 75% judging by the amount of Racoon figures I shot by now (19/25). So far I am satisfied. I hope the final boss on highest difficulty wont be a massive middle finger like Nemesis was in RE3R.