Jeff Wisnia writes:

there really isn't any difference between a
"run" and a "start" capacitor, the term comes from the application, not
the design.

No, these are "different same" items.

Both are typically electrolytics which are compact but lossy. The start
type is rated for a low duty cycle so they can be made very compact and
very lossy (i.e., cheap). The run type must be physically bigger and more
expensive for the same capacitance to make it less lossy, so that it
doesn't overheat in a 100 percent duty cycle.

Weren't they past the phlogiston and ether theory when you studied EE?
Start vs run types vary in the real component of their impedance, which is
reflected in the resistive component of the lumped element model. This is
usually explained in dumbed-down terms of "ripple" for the non-engineer.