What is “vertical casting”? Is this the same thing as “vertical jigging”?

Yes and no.  When fishing for Crappie, there are many variations and techniques of actually presenting the bait or lure to the fish you’re trying to catch.  The “vertical” in both of these terms simply says that you’re dropping the bait or lure straight down and waiting for it to hit the bottom.  You then slowly reel the bait back up, hopefully catching the suspended Crappie on the way.  Casting, however, is slightly different than jigging.  If you’re using a casting technique, your goal is to keep the rod as still as possible above the water.  If you’re jigging, you’re actually moving the tip of the rod in such a way as to jiggle or move the bait to stimulate the Crappie into charging.  Both techniques are popular ways to catch Crappie and I’d suggest you try them both.  Fans of vertical casting will tell you that the Crappie are more likely to take a vertical cast than a vertical jig because Crappie prefer to sneak up on their prey and the slow approach will convince them of an easy target, proponents of vertical jigging say just the opposite.  As you’ve probably discovered by now, successful Crappie fishing is more dependent upon discovering what works best in your particular fishing spot than any tried and true method that belongs to someone else.  The key here to keep an open mind and to be willing to try a few different techniques.