I'm assuming you're thinking of transferring to the 'concert', 'orchestral' or 'pedal' harp, which is a diatonic one. It is tuned to C-flat major and the pitches are modulated chromatically by a set of seven pedals (representing the seven degrees of the diatonic scale) which can be put into three positions per pedal (the chromatic alterations: one position down from 'neutral' raises the selected degree of the scale across the entire instrument by a semitone, one position further down still, raises it by the same again. With all seven pedals 'in neutral' you obtain the diatonic scale of C-flat major I mentioned earlier.

When you do the math, you can see a harpist has multiple ways to set the pedals to arrive at the same diatonic and chromatically altered scales required: one of the many intricacies of playing the instrument is to arrive at pedal control requiring the fewest possible pedal changes to obtain every possible pitch the work in question requires.

So, not trying to put too fine a point on it: you could really not get very much further from a piano if you tried? I think it would be a huge challenge to make such a change (I'm a pianist) but then changing to any instrument other than my own is a pretty mindboggling thought to me as such, anyway. :-/

If the lure of the harp is strong -- it's a glorious instrument in the right hands -- find yourself a teacher where you are, and ask her/him whether they would be prepared to introduce you to their instrument before committing to a change? I'm pretty sure they would be delighted to. (Harpists are a pretty gregarious lot, in my experience.)

(The economical burden of such a change, for one, would be a very good practical reason to 'try before you buy'! Harps do *not* come cheap...)

Hope this helps.