First there are several external factors:Packaging
For YSL rouge volupte, the tube feels very substantial/heavy, I would think its weight is 150% that of the lancome. The decorative band gives a pretty decent representation of the actual color of the lipstick which means you can buy several of them without mixing the color up. The lid, which has a inner plastic layer, somewhat holds the lipstick well so it doesn't come off easily. At the top of the lid, there is also a well made (to see how well made a mirror is, just look at how smooth the edge and how tough the surface is) mirror, in a size that's between a dime and a quarter.
Lancome Le Rouge Absolu comes with a golden tube with blue coffin shaped metal lid, the closure is normal (there is no magnet or suction involved) but the lid doesn't come off easily. The tube is reflective enough for imaging but probably not as handy as an actual mirror due to the color. On the bright side, it doesn't collect finger print like Department of Homeland Security.
Size Both of them are around 4g.
Price YSL costs 34 dollars regularly (but I have seen people buying other shades from those private sale websites and a random nude shade on eBay for 14 dollars) while Lancome Le Rouge Absolu is 26 dollars. Anyway, Satin fuchsia was discontinued last year though.Scent YSL has a creamy, fruity sorbet kind of scent while Lancome smells like grandma (a powdery, flowery artificial smell.)
Color- YSL le rouge volupte #10 is a deep rose while Lancome satin fuchsia is a bright fuchsia that's more blue and a tad lighter than YSL.
Texture- YSL is extremely creamy and soft so I need to be very careful not applying too much while Lancome has a melt-upon-pressing kind of texture that glides nicely without leaving a lot of product.
Finish- Both of them are matte with a very soft focused shine. YSL is so bold that I only dare to wear it as a stain. But Lancome looks good with various intensity.
Conclusion - Lancome is still my favorite fuchsia, although I do love the YSL packaging.Quick lip combo- Lancome Le Rouge Absolu Satin Fuchsia with Revlon Super Lustrous lip gloss in Power Walk Pink