SD and SDHC (and now SDXC) refer the capacity specification of the card. You can read all about it on the
secure digital wiki page. Both the Touch Pro's support the SDHC spec.
Be careful going cheap with your memory cards, you usually get what you pay for. Not only do they tend to be more unreliable, they are usually slower. The one in your link is only a Class 2 (see the wiki). As slr916ek9 alluded to, they are often faked, especially the ones on E-bay.