paul kgyy wrote:

Can someone explain to me the difference between these two approach
types, and how they relate to WAAS?

A sample approach that has both is KARR RNAV(GPS) RWY 9. LPV DA is
956, LNAV/VNAV DA is 990.


LPV requires a TSO 146 navigator. VNAV requires Baro VNAV (only found
in high end aircraft) or, now, a TSO 146 navigator.

With a TSO 146 navigator the VNAV glide-path is not as carefully
calculated as the LPV glide-path. It's as safe, but not as good for
minimums, etc.