Offshore vs inshore is simply terminology | slang used to define the type of species you are targeting when fishing. Offshore is associated with species such as Tuna, Dolphin, Wahoo, Marlin and various species of open ocean feeders. While inshore is referring to fish that live and feed within close proximity to land, Trout, Flounder, Drum, Snook, etc. There is no exact distance, as that varies from one location to the next. Example: in FL you may be catching Mahi within 5 miles, where as in NC you may be 25-50 miles offshore.
Here's a quick Youtube video showing you how to properly prep a ballyhoo, as well as the finishing steps including hook, copper wire, lead weight, leader, etc.