The pedal harp, that gorgeous instrument you see in concert halls and hotel lobbies, is an outgrowth of the folk harp but the relationship stops there. The pedal harp was designed to have a loud voice that will allow it to compete with the other instruments in a symphony orchestra. A complicated mechanism of levers and pedals allows the player to play any incidentals on the scale. Pedal harp players must develop callouses on their fingers in order to coax a good sound out of their instrument.
The folk harp, on the other hand, is a much lighter instrument that can be played by either the fleshy part of the finger, or the fingernails, depending on the style chosen by the player. There is no need to develop calluses, as the folk harp has lighter strings and is consequently more responsive.
The folk harp is a diatonic instrument. To play in a different scale than the harp's native scale (usually C) you need to either retune some strings or use sharping levers, if the harp is equipped with them.
Either harp is a complete, well-rounded instrument. And although pedal harpers can play the folk harp, the reverse is not true. That's not to say that every folk harper should eventually "graduate" to the pedal harp as that would be the same as saying that every violin player should eventually graduate to the cello.
One more point: The pedal harp weighs as much as a small man. A folk harp weighs as much as a 2-year old. And as far as price is concerned, with the money you would spend on a pedal harp alone, you could buy a beautiful Celtic harp and have enough change left over for a new Honda.