I will elaborate a little later on why I "think" Pac dunes may be easier, to me.
I absolutely love both courses. I've played 4 rounds at both. It may be that I played Ballyneal much more recently than PD.
I find myself naturally comparing the two all the time. For me, Pacific dunes has three relatively easy birdie par 5's, I believe easier than BN's because of the green surrounds (i.e. 4 and 8 can be tough pitches at BN).
Both courses have wide fairways, but BN's are a little more elevated and exposed to the wind.
And the hardest holes at BN are harder than the hardest holes at PD, in my opinion.
It isn't by a wide margin, but I believe PD might be just a touch easier.