both those systems are just, not very great.
but the sempron is a more powerful processor than the Celeron.
they both have onboard video, which is not very good. by the looks of them, the Power Supplies are not very good either. (Power Supplies are an important part)
I'd recommend that if anything, you spend a bit more money and get an upgrade more worthwhile.
if you would like to learn, you can even build your own PC
although there are several places that will build a PC for you, with parts of your choice.