The difference being regulated 22OVAC - 12VDC regulated power supplies will show up in how well conditioned the V and I ripple voltages coming out and V and I switching transients are .
A cheap and nasty (or poorly designed) RPS will have significant ripple in either or both of V and I outputs, this can have deliterious effects on your circuitry.
http://upload.wikimedia.org/wikipedi...pple.svg/400px-
A better RPS will have very small V and I ripple , and may even he ripple tuneable to suit the needs of the devices connected to it.
Only way to know for sure is to get hold of the Spec Sheet for the RPS and look at the guaranteed max ripple in Vout and Iout , or to connect the RPS to good oscilloscope and measure it yourself.
Also important to know is how big the V and I transients are when it switches - in fact these can be more important than the ripple V and ripple I as the transients occur over very short periods and can really hurt circuits connected to the RPS.
You might see something like
http://www.national.com/ds/LM/LM317.pdf