The below is from the link to the finish descriptions right from the eyeshadow page on the MAC website. You just click on "Finish Descriptions" and you get a popup with the below info in MAC's own words.
EYE SHADOW FINISHES
FROST
An iridescent shine that adds a highlight to any colour.
LUSTRE
Smoothly pearlized; intensely frosted with deluxe ultra-fine "conditioned" finish.
MATTE
Hi-colour pay-off in a no-shine matte finish.
MATTE2
Intense, opaque matte finish with exceptionally rich colour payoff.
SATIN
Pure colour in a satin-style finish. Provides a soft subtle non-frost, light-refractive sheen.
VELUXE
Superfine pigment rich and very luxe. Supple to apply. Provides silky smooth matte finish.
VELUXE PEARL
Vibrantly-toned. Velvety soft. Shimmeringly metallic. Veluxe eye shadow, now overlaid with high-shine pearl.
VELVET
Soft look finish with high-colour intensity. Has a plush velvety look and feel.
The actual link to the popup is...
M·A·C Cosmetics | Finish Descriptions