Well, they're not the same techniques, but the techniques are in the same field, compared to, say, standup or scripted theatre. Short form is closer to long form than it is to either of those, I think. An long form improviser would have an easier time performing short form than performing Macbeth, and a short form improviser would probably prefer doing long form to doing standup. It's apples and oranges, but both are fruit that grow on trees!