The above, if it were a joke, would be something like, "This joke is kinda lame," I shall make fun of it." Trolling would be like, "I disagree with your viewpoints, therefore I shall be a dickhead and go out of my way to make you feel bad."
That's how I would explain the difference. Trolls are just scumbags, poking fun at a joke by LIGHTHEARTEDLY criticising it is joking. There is a difference, and in today's "Oh, muh feels" lack of reality, it's hard to say that any statement, no matter how ridiculous it is could offend somebody. Context is missing. That's why I try to not immediately judge a seemingly critical comment without asking the author the intent of the message.