Pop (Rock Piano)
The difference between classical and pop/rock piano is the fingering
patterns which were developed for the former hundreds of years ago.
Even someone as pop as Billy Joel has regular classical technique
though he does not always use it. There is a difference in the way
rhythm is handled in both. In classical way of learning, you learn by
reading notation (aka 5-lines scores or stave readings). This is just
like learning a new language.
In pop/rock way, we focus on listening and expressing what we hear. Just like singing, one needs to learn how to sing the song by listening to it over & over again and then with the help of our innate senses one usually expresses the notes through their voice. Definitely a much enjoyable process to learn.
However, If you learn how to play classically, you can quickly learn pop music afterwards. Although, some professional support from a trainer could be advantageous since it will show you the first steps of ?groove? on the piano. The song ?I need a Dollar? (Aloe Black) serves as a good example, providing you with a wide scope for instance.
In pop/rock way, often creativity and improvisation is encouraged. For example, if a particular song is too complicated in its original recordings, one could improvise it a little to play in a more simplifed 'cleaner' version. Sometimes, even vice versa!