To be clear...
...the author of the graphic in question (Emily Lakdawalla of The Planetary Society) describes it as an "asteroids-and-comets-to-scale montage".
Space/Science » in reply to Comet nuclei are asteroids????????
...the author of the graphic in question (Emily Lakdawalla of The Planetary Society) describes it as an "asteroids-and-comets-to-scale montage".