Whilst they both claim to have 5% glycolic acid, Pixi is more soothing and Nip & Fab (N&F) is more aggressive with addition of Lactic (14th), Salicyclic (13th), Mandelic (11th) and Hyaluronic Acids (19th). I think Pixi would be great for acid beginners but N&F would need more experienced skin.
Plus N&F’s second ingredient after water is Glycolic whereas, Pixi has Glycolic listed as the sixth ingredient followed by other ingredients which would help in calming the skin. ✨N&F also has Niacinamide (6th ingredient) which is a powerhouse ingredient (helps with ageing skin, enhance skin barrier, helps with skin tone and texture).
✨All in all, I think they are for individuals with different skin tolerance, and if you need something tad more aggressive N&B extreme (as the name suggests) would be good choice. Having said that, our love for Pixi Glow Tonic is eternal (forever reliable product)✨💝.