Differences in Michelangelo's David and Bernin's David can be seen the instant you set eyes on them. Bernin's David was constructed during the Baroque Era when the artists were not focusing on making the perfect body and the artists were not obsessed with make every little detail look perfect.When you look at Bernin's you can tell it is not perfectly sculpted such as Michelangelo's. Michelangelo's David was constructed during the Renaissance where perfect bodies were the focus. Michelangelo's piece is very detailed and almost perfect. There are hardly any flaws in his form because of how Renaissance art was focused on the supposed perfect body. Bernin's piece is a perfect epitome of the Baroque era. He is trying to show his skill and knowledge of the body with his piece. With the different stance David is taking he is showing off his skill as a sculpturer in the ability to move muscles the way they ought to. It also shows the Baroque Era idea because the piece isn't perfectly standing. This was introduced in the Baroque Era because of how they were breaking off from Renaissance Era art.
Another difference, I believe, is that during the Baroque Era, the Catholic Church was trying to get their members back and Bernin's piece illustrates a story from the bible, David and the Golith. I believe this has to do with the Reformation because of the obsession with art that shows spiritual stories.