The brushes are the same as far as I can tell. The felt tip makes for an easy application. However, I do find the Loreal handle more difficult to deal with. It is more wide at the base than it is at the top, which is a little more challenging for me to use and makes my line less precise. The Lancome handle is also a little shorter and is the same size from top to bottom. The shades are also different. Loreal is less black and less intense. Lancome's Noir is much more black and bold. Kind of an Urban Decay Zero and Perversion situation. As far as staying power, Atrliner seems to last longer and holds its color better. I probably had the same tube of Artliner for nearly a year and I wear black liner maybe 2-4 times a week. I have used Loreal Lineur Intense twice and I can already tell it will not last near that long since I have to apply 2-3 coats to get the intensity I want. Lancome's Artliner is $29.00 and Loreal is $7.00. Large price difference, but I would rather buy one quality liner once a year vs a liner that is not as good two or three times a year.
In both pictures, Loreal is on the left and Lancome on the right.