What is the difference between open heart surgery and bi pass surgery?

The term "open heart surgery" is really used incorrectly.

We use it to mean a surgery where the chest is cut open to get the heart.

A "bypass surgery" is where they cut open your chest and reroute the large blood vessels (arteries) on the outside of the heart.

We do wrongfully call Bypass Surgery a type of Open Heart Surgery.

But I would call a real "open heart surgery" where they cut open the chest and then cut open the heart to work inside the heart, like replace valves.