Colour swatch on my wrist. L - Sleek 'Rose Gold', R- Accessorize 'Bronzing Block shade 3'
As you can see from the colour swatch, the Sleek blush is a lot more delicate, with a metallic-y/shimmery finish. The Accessorize blush is darker but also contains a hint of shimmer. I particularly like both of these blushes as they are very pigmented, meaning that it only takes a sweep or two to get a good colour on your skin. They are both very similar to Nars 'Blush' in the shade 'Orgasm', however, at £21 a pop I actually think these two cheaper blushes are much better value for money & are actually better quality products. I no longer use my Nars blush in that shade but I can see these two being a staple of my make-up bag for the foreseeable future :)
Both products are available in store at Superdrug (although, unfortunately, they're not on their website) + Superdrug is currently doing 3 for 2 across all their cosmetics so you can buy these two blushes & choose another product for free :)