KMid2 plays MIDI and karaoke files to hardware MIDI devices or software synthesizers. It supports playlists, MIDI mappers, tempo (speed) control, volume and pitch (transpose) controls, and configurable character encoding, font, and color for lyrics. The graphic views include a rhythm view (visual metronome), a channels window with solo/muting controls and instrument selectors, and a piano player window (pianola).
Virtual MIDI Piano Keyboard is a MIDI event generator and receiver. It doesn't produce any sound by itself, but can be used to drive a MIDI synthesizer (either hardware or software, internal or external). You can use the computer's keyboard or mouse to play MIDI notes. You can use the Virtual MIDI Piano Keyboard to display the played MIDI notes from another instrument or MIDI file player.