The Hawkins has a wooden stock, brass patch box, brass nose cap, brass butt plate, fancy stock, and they are the fancy top of the line models. They have a 28 inch barrel with a 1-48 twist. Their .50 caliber is 15/16th on the flats. Their .54 is 1 inch on the flats.
The Renegade is a wooden stock, no brass, 26 inch barrel. While they are not decorated, they are a work horse rifle. Also they have a little higher raise in the comb on the stock. All their calibers are 1 inch on the flats.
The New Englander is the plain jane of the sidelocks. They can have a wooden stock if it is an older model, but most of them have a black composite stock. They are well made, good shooters, just not fancy. A real meat and potatoes rifle. All of theirs is 15/16th on the flats I believe.
I have all three of the above rifles. All of them are great shooters. I personally like the Renegades, but for comfort shooting, the Hawkins is a better rifle to absorb recoil.