All Omega-3s are created differently due to the process of detoxification of fish oil and their chemical structure. This difference affects their bioavailability and thus clinical efficacy.
In this video clip, Dr. Friedman explains what form of Omega-3 is the most absorbable and clinically proven to work.

Dr Kimberly K. Friedman, OD FAAO
Kimberly Friedman, OD is a founding partner of Moorestown Eye Associates, a private group optometric practice in New Jersey, and the Director of The Dry Eye Clinic at Moorestown Eye. She is a past president of the New Jersey Society of Optometric Physicians, a fellow in the American Academy of Optometry, a Diplomate of the American Board of Optometry, and a past Clinical Director for the NJ and National Special Olympics Opening Eyes Program.