I have no idea, I fly P47-D30.
D25 is said to turn better...maybe... I don't fly it. the D30 has dive flaps, that I rarely use anyway.
D30 supposed to have 300 more HP when using Wep, I don't think it's implemented in AH.
Big diff is the paint job, it may looks silly but the D30 is easier to see because it's silver. When fighting, it's always easy to know where it's going. The D25 is dark green and "melt" with the ground color, making it hard to see where it's going or how it's moving, especially at night.
I prefer the gunsight of the D30 better too, but I suck at shooting moving stuff.