Musician

A musician is an artist who is skilled in any kind of instrument. It may or may not be the person's profession. Musicians can be classified by their roles in performing music.
An instrumentalist plays a musical instrument.
A multi-instrumentalist plays a diverse range of instruments such as different forms of percussion, plucked strings, vocals etc.
A singer is a vocalist.
Composers, songwriters and arrangers create musical compositions, songs and arrangements. These may be transcribed in music notation, performed or recorded.
A conductor leads a musical ensemble. A conductor can simultaneously act as an instrumentalist in the ensemble.
A recording artist creates recorded music, such as CDs and MP3 files.
( A composer is always a musician, but a musician is not necessarily a composer.)
There are many forms of musicians. From classical artist to rock artist. The spectrum is so diverse that there is no limitation to a musician's qualifications.