A plug is just pouch tobacco pressed into a "brick". It just makes it more compact and you bite of what you want.
I chewed when I was kid and dipped from the age of 10 until I was 35. Hardest thing in the world I ever had to quit. I smoked once also and it was 10 times as easy to quit smoking than dipping to me. I had tried to quit dipping many time over about a 10 year period and never made it past a week.
I have not had a dip in 4 years now and I still get cravings and triggers out of the blue, but they leave as fast as they come.