The harp is a member of the string family, with its own sub-class of instruments. There are many types of harps, so there is no set number of strings. The first video here is of Mark Harmer on the Celtic harp playing Carolan's Dream. This performance is so touching.
The second video is Josh Layne playing the Grandjany cadenza from Handel's Harp Concerto.
I wouldn't go so far as to say this is a comparison between a "folk performance" and a classical one. Harmer has everything nailed down so perfectly. I've heard many harpists over the years, and Mark Harmer beats them all, hands-down, in every respect. The tone of his instrument is as pure as a mountain spring, and he has it tuned to perfection. It's rare to hear someone who just gets it all this right.
Mark is available on iTunes...what a treat! Link to it from here to help support our class: