Actually...
I usually say sales are more important than position, it is, for the music freaks like us. But for an "average" person, if you'd tell him that album X sold Y, he'd say: "Why are you telling me this?"
But, if you say, for example - Teenage Dream (album) by Katy Perry went #1. The Fame by Lady Gaga went #2. TD would sound more impressive. If you'd say,
TD by Katy Perry went #1 and sold 500,000 copies, and The Fame by Lady Gaga went #2 and sold 4,000,000 copies, TD would still sound more impressive.