There were no rifled muskets in the Revolutionary War. In fact, some rifles had their rifling bored out so they were smooth bore rifles.
Muskets fired an undersized ball (loose fitting to the barrel) and was quick to load but considered by many to be inaccurate. Hence, the dense infantry formations and the reliance on linear warfare to maximize the effectiveness of shock. In reality, muskets are accurate out to 75 yards (or 100 on the figure of a standing man if the soldier practiced and benchrested his weapon). Unfortunately, most soldiers were not trained to shoot and were only drilled in loading and dry-firing. There are exceptions, but they are few.
By contrast, rifles feature a barrel that has grooves cut into it, called rifling. A fitted ball, sometimes undersized and wrapped with a greased leather patch to ensure a tight fit to the bore, is rammed down the barrel. When fired, the rifling imparts a spin to the ball (think of a gyroscope), making it fly further with greater accuracy and energy retention. It was not uncommon for a rifleman to hit a man at 200 yards, twice the distance of a musket. When laying down or resting his rifle, good riflemen were capable of hitting at 300 yards and some of the best at 400. The disadvantage of the rifle was the loading process. It was very slow. Whereas a musketman could fire miminally three rounds a minute (four or five when well drilled), the rifleman could only fire about one round a minute. This put the rifleman at a disadvantage at close range (75 yards or less). Furthermore, as most rifles were not fitted with bayonets, the rifleman could not engage in close quarter combat (forget what Hollywood showed in The Patriot) against a musket man who charged with fixed bayonet. The Battle of Long Island (also known as the Battle of Brooklyn) on the Revolutionary War illustrated this example when the Hessian infantry chased off the vaunted American rifleman (and even pinned a few to trees).
Rifled muskets are altogether a different thing. A rifled musket is musket whose bore was rifled subsequent to its production. This was done to adapt the musket to the new minie ball. By contrast, a "rifle musket" begins its life as a rifled firearm.
Joe Bilby (among many other authors) discusses this in his new book, Small Arms at Gettysburg.