The photon 32 has a two year American warranty, since you are actually giving money to an American man to purchase the product. By buying the Evergrow unit, you are giving money to the Chinese who do not have a warranty. The units are almost the same, I think, but it's a personal choice... I would rather have the warranty and get help with the unit from someone who speaks English well.
Degree optics is how concentrated the led light beam is. The more concentrated, the higher PAR and PUR. Generally, the narrower the beam, (60*) the more spotlighting/disco effect happens. The 120* optics blend the colors better. Also, these little units are VERY powerful, and you don't need to use optics that are too narrow unless you are placing the unit way above the tank.
For a few dollars more you can get the unit customized with different colors and change out the colors of the moonlights (if you do this, they switch it from Royal Blue to neutral white. Do not get neutral white - it's way too yellow for moonlight. Get cool white moonlights if you decide to go with a much whiter, more natural look.