render man and pixar artist tool

[comp arts]

can any expert one in maya tell me
whatis the difference between maya pixar render man and artist tool

i know maya render man 4.5 is plug in for rendering
so what is the difference between it and the artist tool

i listen that maya rendering is not good rendering and any one is using maya make the render on render man
is this wright

and which is better maya renderin (oreginal without plug in) or 3d studio max 5 rendering

tell me please