They're two different creatures entirely with a fair amount of functional overlap, depending on the cutting conditions, bar length and operator.
The 9010 has a boatload of torque and will both pull and oil a 42" with aplomb in just about any wood in N.A, including Hedge (though I'd definitely want a skip chain). The 390xp has a decided RPM advantage in 28-30" wood and less pulling a 24-32" bar very well. YMMV. If you're heavy handed, dogging the saw in to cut, the 9010 will run away from a 390. With a good chain in <30" wood, letting the chain cut on it's own, the 390 will walk or run away from the 9010 depending on the wood density.
For my use my ported 372 runs a 28" bar decently but 24" is about perfect.
A 390xp would be a 28" saw which could also run from a 20-32" bar very well.
the 9010 sometimes wars a 28" bar but is more at home with it's 36" bar. I don't have a longer one as I just don't need one, nor do I want to file that many cutters when I find a nail in a tree on accident...