Have both
Speaker is much louder on the P30 Pro, twice as loud and better clarity+quality too, speaker is better even though it's a single speaker. It sounds like a bluetooth speaker (better clarity and separation than S10+) whereas Mate 20 Pro's speakers can't really come close.
No notification LED but the AOD shows notifications for third party apps now.
FPS is faster than the one on the Mate 20 Pro.
Colours are better on the P30 Pro but resolution isn't as high. (Both use BOE panels btw Mate 20 Pro uses both BOE and LG, P30 Pro uses BOE, regular P30 uses inferior Samsung. It's always been BOE>Samsung.)
Battery life is better on the P30 Pro as well.
Keeping the P30 Pro and selling the Mate 20 Pro.