Expect about the same power from either
. . . the onkyo tx-sr507 and the yamaha rxv465 . . . the yami is 105 watts and the onkyo is 80 is that a huge diff . . .
Short answer is no. Manufacturer quoted power, especially at the budget end of their respective lines is not much more than a WAG (wild *** guess) mainly for marketing purposes.
A simple, and in this case more accurate, measure of expected power is the products weights (higher power generally takes beefer/heavier power supplies and components) and both units you are considering weigh in at ~20 lbs--so you will not find a noticeable difference in power.
Looking at their back views, they have nearly identical connection options, but the Onyko does have better speaker connectors for the surrounds and center channels.
I own a Yammy RX-V563 and the "Scene" buttons on the front are very convenient. One button push selects; the proper source (DVD, CD, TV, Radio), sound program, and video routing--pretty cool, especially for "techno-challenged" family members. You can customize the Scene buttons to best suit your needs (sound program, video route (HDMI, Component, etc.)).
Sound wise, I don't think you could tell them apart if double-blind tested. I suggest you look at each receiver's manual online, to see if either one's user interface/controls seems more logical to you.
Good Luck Hunting,
XEagleDriver