Some power supplies just supply superior quality power. This is measured in terms of voltage regulation & ripple (basically how steady & constant is the power provided, vs inconstant power with slightly higher spikes & dips).The 'dirtier' the power supplied by the power supply, the higher likelihood it will slowly degrade components over time. Also, some power supplies can't really deliver their rated wattage - the companies fudge their numbers or simply lie. For instance, the Rosewill Green 430w can probably match the maximum power output of the Rosewill Stallion 500w, but the Stallion paints a larger number on the box. Unfortunately, there's not really a way to tell the difference between good & bad PSUs right off except reading power reviews. Or just looking inside if you're really knowledgeable. Thankfully you can come here.
Long story short, the Rosewill Green series provides higher quality power than the Rosewill Stallion series. Stallions are cheap, relatively unreliable brands. Greens are middle of the road, good budget performers that you don't have to worry about. Stallions will generally work, particularly if you get a wattage level high above the amount you really need (taking into account cheap, poor-quality power supplies is why most online power calculators recommend far higher wattage than you really need, like nvidia recommending 550-600w PSUs to power one GTX 560 or something ridiculous like that). But there's a higher risk, and no real penalty for getting a higher quality power supply, since some quality line like a Rosewill Green or an Antec Neo Eco or something is usually available at the same price.
For motherboard, if you're not overclocking, it's meh, whatever. You're not going to stress the board and you won't see any performance difference. Heavily overclocking, and motherboard choice actually matters a bit. For instance, that's when solid capacitors might actually matter.