MIDI is an industry specification for encoding, storing, synchronizing, and transmitting the musical performance and control data of electronic musical instruments (synthesizers, drum machines, computers) and other electronic equipment. wikipedia.org

An arrangement of a musical composition is a reworking of a piece of music so that it can be played by a different instrument or combination of instruments from the original. wikipedia.org

Music engraving is the art of drawing music notation at high quality for the purpose of mechanical reproduction. The term music copying is almost equivalent, though music engraving implies a higher degree of skill and quality, usually for publication. wikipedia.org

Sibelius is a scorewriter program for Microsoft Windows, Mac OS X, and RISC OS. It is used by composers, arrangers, performers, music publishers, teachers and students, particularly for writing classical, jazz, band, vocal, film and television music. wikipedia.org