This type of handlebar creates a more aerodynamic shape with the rider’s body. This means you will be able to go faster since the transfer of energy forward becomes more efficient. There are also more places to put your hands creating numerous riding positions. One thing to consider with drop-bars is the position of your back if you are a less flexible rider, stretching off the bike will help make this easier.
Flat-bar handlebars create an upright riding position. This allows a rider greater ability to see the road ahead more clearly and have less pressure on their lower back.