Exactly. The “P” of the last item stands for Power
DEF 5V #PWR 0 0 Y Y 1 F P → Power symbol
DEF R R 0 0 N Y 1 F N → Other than power
Nearly. It is not to identify libraries but symbols. If the library has mixed power and “normal” symbols, the add power symbol dialog will show only the power symbols no matter which library they belong to.