Not an expert in this. In some fundamental way, icons have a specific function. To convey action, or status, etc in a small compact graphical form. Semiologically, photoshop tools palette icons and app icons are functionally the same. They are both used to perform an action whether that’s to select a tool or launch an app.

Edit: one key thing I forgot about iconography - familiarity. The floppy disk icon is ubiquitously understood for historic reasons.