Golf instruction in recent decades has gone through many stages and created many buzz words. Most of the buzz words are terms taken out of context that develop a life of their own, such as "big muscle swing" or "covering the ball". Many of my students are confused by these terms and I find it helpful to simplify the learning process by teaching two basic swing types, upright and rounded.
I am very fortunate to have trained with Jim Hardy, who I consider to be the best teacher in golf. Hardy, who taught for years with John Jacobs, originally learned to teach upright swings in all their golf schools. Over the years, however, he was able to figure out how players like Lee Trevino and Ben Hogan were such great ball strikers and yet used very flat or rounded swings. By understanding these two styles of swings, he was able to also put them in the categories of arms dominant, or upright and body dominant or rounded. If you are trying to figure out a swing that will work for you then you must decide if swinging more up and down with your arms feels more natural than swinging around your body.
Very often former tennis and baseball players like the rounded, body dominant swings. It simply feels more natural to them to turn their body for power while upright players use their arms as a main source of power. Of course, it makes no difference which one you choose, because the Golf Hall of Fame is full of players who use both techniques. What really matters it that you like the feel and performance of your swing more than the look or style of the motion.