When the aim is to fix something, the assumption usually is that something is broken.
When the aim is to improve something, the here and now is a starting point without qualitative assumptions.
In both cases, the assumption is that the investment is worth it and that improvement can result.
Fixing has an endpoint. Once it is done, it is done.
Improvement has no endpoint. It is a repeatable process.
Do you learn to fix or to improve?