Very different--check the review to see how.
I compared the It Cosmetics Bye Bye Under Eye Eyelift in a Tube in the shade Medium and the e.l.f.Cosmetics Under Eye Concealer & Highlighter in the shade Medium Glow. The It Cosmetics is $29 for 0.36 fl oz of product and the e.l.f is $4 for 0.4 fl oz. Both products claim to cover circles and lines around the eyes to provide a smooth eye area. The It Cosmetics concealer has a brightening formula on one end that you apply to the under-eye area before the concealer on the other end. The e.l.f. concealer is also a 2 step system where you use the concealer part and then follow up with the brightening end. The It Cosmetics concealer offers crease-free coverage that really does last all day and it blends beautifully. It didn't even look like I had concealer on. It just looked like I had perfectly smooth under eyes without circles or lines. I used it multiple times and it looked beautiful with or without foundation as well as without having to set with powder. The e.l.f is more of a salmon tone which is great to conceal dark circles but it was still quite 'orange' when it dried. Even after adding the brightening step on top it seemed to emphasize the lines around my eyes. I did try it a separate time applying the concealer sparingly to cancel out dark circles and then dotted another concealer on top of it and then the brighteningand it covered beautifully without having to use a powder to set it. In conclusion, I think the It Cosmetics is the much better option and worth the price tag. No competition!