Private vs. Commerical Approach Speeds

Spent last week recharging by the pool in the Lake Las Vegas Area (8-10 miles east of McCarran). A majority of the planes were landing from East to West and we were able to watch them coming in for both runways. The interesting thing was that the private jets seemed to be traveling significantly faster than their commercial counterparts, and they were also noticeably louder. In fact, my brother and I could almost call out whether it was private or commercial without looking due to the sound.

Was this just an optical and auditory illusion, or do the private jets have much higher approach/landing speeds and less noise compression than the commerical jets?

Approach speed depends, among other things, the aircraft size.

There is also an optical illusion factor. A 747 flying at the same size and distance from viewer as a Citation will appear to be going slower because of its size.

Many private jets are louder than airliners.