What is the difference between having a heart murmur and a mitral valve prolapse?

Sometimes related . Mitral valve prolapse is a diagnosis which describes how the valve closes. A heart murmur is a physical finding (sign) it is not a diagnosis. A heart murmur is a sound you can hear when blood flows with turbulence (rough flow like rapids in a river). Murmurs can be caused by many things. The location and quality often gives us clues to what caused it. Prolapse may or may not have a murmur.
Simple. Murmur= an extra heart sound beyond the expected lub dup. Mitral valve prolapse= the mitral valve sinks in when it closes and may leak. You hear a murmur, which may be a problem or not. You usually won't hear a valve prolapse but find out about it on a cardiac ultrasound or catheterization.
Heart murmur. Could occur in same person. Murmur is detected by auscultation by listening to heart beats with stethoscope. Mortal valve prolapse is seen on screen by doing echocardiogram.