EV = LV at ISO 100.
As I understand the term in simple language, EV is how much light is falling onto something, like film.
By contrast, LV is a measure of the subject’s absolute brightness, or how much light the subject is emitting.
So move your aperture ring (only), or change your shutter speed (only), and EV will change – but LV will not.
However, light bouncing off a black cat will have a different LV than the same light bouncing off an orange cat.
Hmm. Now that I think about it, one can say that the Pentax Digital & Pentax Spotmeter V (w/ their ISO-100 values) read directly into LV.