One describes a state of well-being, and the other relates to the ability to perform a certain task, such as running a 5k.
It is possible to be of healthy mind and body and of no interest in running a faster 5k. Similarly, you can run a faster 5k and not be of sound mind and body.
Sadly, because it’s easier to measure fitness than it is health, it is easy to forget the order in which to put things; fit and unhealthy is not as helpful as being healthy and fit.