Piano is essentially a percussion instrument, it is deemed so because there are a set of 'hammers' which strike the strings-firm felt hammers on wooden rods. read more
Both the Piano and Guitar complimenting the other. And this is the point: the expressive range of Guitar occupies a different landscape to that of Piano, it is neither more, or less expressive, just different, and they can certainly play together in effective and beautiful ways. read more
The guitar is more expressive. Techniques like bends, hammer-ons, pull-offs, harmonics, vibrato, slides, and trills can really make the guitar "talk." The piano pales in comparison. read more