MAC Duck is a very warm-toned, dark brown with a matte finish. It is a permanent eyeliner that retails for $16.00 and contains 0.04 oz.
MAC Duck Powerpoint Eye Pencil ($15.00 for 0.04 oz.) is described as a "soft grey brown." It doesn't read gray at all to me; it's more of a warm-toned, medium-dark brown with hints of red in the base. It has no shimmer, so the finish tends to look more matte on the lash line. Chanel Brun-Teak is similar but darker. MAC Brownborder is also similar and only slightly darker.
Waterproof. Longwearing. Metallic, shimmer and matte finishes. Smooth to apply. Won't transfer, smudge, or budge... Draws the line: powers your eyes. Makes its point. Lasts.