Almot,
Both the "Liquid Rubber" that you linked to, and the "Liquid Roof" product that I used are both made by the same company - ProGuard. I suspect that they are the exact same product but can't say for sure.
Both product guides say they are to be applied as a 20mil thick coating and the coverage is the same for both.
However, the warranty for the Liquid Rubber product is two years, while the warranty for the Liquid Roof product is five years.
Here is a copy/paste from their website about the two.
"EPDM Liquid Rubber®
Liquid Rubber has the same chemical make up as Liquid Roof and therefore can be used for applications where you would use Liquid Roof. The differences between the two are a slight color difference, where you can purchase the product and warranty."
Barney