They are both price changes in response to a 1 bp change.
DV01 is valid for a single bond. It is the price change in response to a 1 bp change in yield of this instrument. It arises from the mathematical relationship between yield and price.
PV01 is a more general concept for all fixed income securities , not just bonds but swaps, futures and options, MBS, and portfolios thereof. It is the price change in response to a 1 bp change in yields all along the yield curve (parallel shift in the yield curve). It presupposes an estimate of the yield curve and a mathematical relationship between the price of an instrument and this yield curve.
For a single simple bond they are the same.