Both a bypass operation or surgery and the open heart surgery involve a surgical procedure on the heart. However, there are certain differences between bypass surgery and open heart surgery. The bypass can be a certain type of open-heart surgery. However, there are many other types of open-heart operations besides bypass surgery. Specifically, the bypass surgery will take a tube from the body and move it somewhere else.
There are a few types of bypass surgeries, including vascular bypass surgery and cardiopulmonary bypass. These are usually not voluntary surgeries, but a weight loss surgery that does not involve the heart is most likely voluntary. Open heart surgery may not be rerouting anything. It could be placing a stint in the heart or another type of procedure.