The Clubmaster is a browline frame: a heavy top bar and a thin metal rim under it, which is why it reads as spectacles rather than as sunglasses. The original does that bar in acetate and the RB3716 does it in metal. Acetate is thicker and darker, so it draws a firm line across the face — good if you want the frame to be the statement, heavy if your features are fine. Metal is thinner and see-through at the edges, so it does the same shape without the weight. Size follows the material here: the classic is 49mm and reads period, the metal is 51mm and reads current.
Bridge fit decides this more often than taste does
Both of these put their pads high, which is what makes a browline frame sit where it should on a high bridge and slide all day on a low one. Ray-Ban publishes low-bridge versions of the Clubmaster for exactly this reason, and they are a different product rather than a different size. If sunglasses have always crept down your nose, that is the thing to solve before choosing between these two — neither of them fixes it.
One is a browline, both are the same lens
It is easy to read the metal version as the lighter-duty one. It is not: the lens is the same G-15 in both, cut to the same curve, and the difference is entirely in what holds it. Choose on the bar and the width, not on any expectation that one is more or less of a sunglass than the other.