hmm that's right.
but there are various types of pianos and organs today.. aye hmm
lemme try too.
organs, if you're referring to pipe organs, they are wind
instruments as skeujin mentioned. But as some people refer to the
electone as an organ, specifically the electone organ, this one
runs on electricity.
The electone organ is similar to the keyboard, just that the organ
comes with pedals of up to one octave or more if you like [but not
too many], and has more options such as the combinations of sounds,
types of instruments and rhythm beats, allows recordings, allows
you to preset different combinations of instruments and the list
goes on....
Pianos are hmm I think considered percussion instruments, though
the sound is produced by hitting the wire thingy behind, but since
it's HITTING it's percussion 
Pianos nowadays sometimes run on electricity too, in the
case of a silent piano [which can be used as a normal piano without
the headphones too]...
I don't exactly know very well.. I'm sure there are others who can
give better explanations 
