The Pacific Pectin Company, which manufacturers and markets verious kinds of pectin, has a FAQ page on their website. If you don't find your answer there, contact them. They may be gald to add that information to their FAQ page.
As chowmel indicated, in ordinary jam and jelly making the only difference in using the ordinary pectins is the order in which they are added. However, there are lots of pectin formulations on the market now, including low-sugar versions that require calcium to gel. So not all pectins are equal.
I'm not sure about candy making, but they are both used in making jams and jellies. The difference in when they are added to the fruit. I generally use liquid pectin if I'm using pectin because it's added after the sugar is added to the fuit. I like the sugar and fruit to warm together first.