Yes 150 FPS diff, many times closer to 100fps diff. with handloads to equal pressure.
The killing power diff. is a non-issue, kinda like comparing a an 19-20" 308 & a 26" 308, the killing power is not in a different catagory, but could only say that one has the same energy at a slightly different range.
As far as accuracy is concerned, if either round is used for a custom build, either can be more accurate than the shooter, both are extremely accurate. Yes, you hear of far more accurate 300 Wim Mags, but there are far more 300Win Mags too. If you ask Sisk rifles or Jarrett which is the more accurate, you will be told the 300 Win mag, they have no reason to lie that I am aware of & is noteworthy.
I have had both & like both, but I sold the Wea. & kept the 300 Win, no regrets. It is also noteworthy that the Military are converting many M24's to 300Win Mag & is highly regarded as precision rifles. Long range shooters who have rifles built for them will pick the 300 Win easily 10 to 1 over the Wea.
Also, it is much easier to buy quality brass for the Win.