Here’s what Subdivide Edges and Collapse Edges do:

The same stroke made with different settings.
Subdivide Collapse does both.
Subdivide Collapse is usually your best option, but when (‘famous’ use case) Pinching a Crease for instance, you will want to switch to Subdivide Edges.
I recommend playing with those settings for some time, while having the Wireframe (set to 1) Overlay enabled.