A dedicated sound card would offload the sound processing from your CPU and onto it's own dedicated processor.
A video card does the same in terms of video.
And "all the specs" determines how good the cards are. In video cards, you can only directly compare specifications in the same generation of cards. For example, if you are looking at the ATI 4000 series, you can compare any card within that series (4670,4850, 4870, 4890 etc). You, however, cannot accurately compare a 4000 series card with a 3000 series card directly from specifications.
And you can check what kind of graphics card you have by typing in dxdiag into the run/search bar or going into display properties.