Artist - individual recording vocals with music accompanyment and performing the song live
Musician - individual who plays live instuments (piano, guitar, bass, drums, wind instuments)
Songwriters - wrote song "Lyrics" to be recorded with music
Composer - performs/writes an arraignment of notes & measures with instuments"Music"
Studio engineer - individual at mixing console recording vocals with the music
Producer - individual responsible for producing the track (song)
Executive producer - organizes all the the above, covers the cost and owns "the master recordings"
*Songwriters can be Composers the same individual
*Producers hold muliple roles as well, composer, studio engineer, associate with recording artist and own their own recording studio. Hence they have all the elements to produce a song (Producer). Example "Hitman" works in "Aftermath" studios he receives production and credit but, "Dr Dre" puts the finishing touches on the track and oversees the production making him 'Executive producer". (Footnote)
Footnote:(Some also write lyrics and play actual instruments giving them performance credit as a musician and publishing as a songwriter of lyrics, making them "self produced".)