What are the differences between Latisse and LiLash? Which is better?

Only Latisse is medically approved to lengthen and darken and thicken lashes.
There are many imitations and claims; it is buyer beware.
Dicuss this with your doctor. He /she will give you a good advice.

Lilash and most other Latisse competitors have had to remove the active ingredients that mimic the prostaglandin analog in Latisse. So most, if not all, of them no longer have any ingredient known to enhance eyelash growth. Latisse is the only FDA approved and clinically proven medication to grow longer, fuller lashes. I've written a breakdown of the available products today and where they stand on active ingredients, linked to below.

Latisse is a clinically studied and proven product approved by the FDA. Any product that has true medical RX-controlled ingredients must have this safety study and Latisse has passed that rigorous investigation and study requirement.
In 2008, the FDA Dermatologic and Ophthalmic Drugs Advisory Committee voted to approve bimatoprost for the cosmetic use of darkening and lengthening eyelashes
Latisse contains FDA approved Bimatoprost. Bimatoprost (patented by Allergan) prolongs the growth cycle of hair and does so with the most safety.
Any product with true prescription ingredients requires a doctor's prescription. And for good reason. There are certain eye conditions that would prohibit the use of hair growth stimulators and unless these conditions are ruled out, you could be playing dangerously with your eye health.
Results aside, you would be wise to stick with FDA approved products when applying any product with medically active ingredients to your eye area.