FWIW:
1. Ammonia is Ammonia. It is a nitrogen atom connected to three hydrogen atoms. It is very caustic and you need to take care in whatever use you put it to.
2. "Blue" is a nickname alerting you to how the particular batch was made. "Blue" means that the Ammonia was made by the process using "Blue" hydrogen. That in turn means that the hydrogen was made from some carbon-containing stock (usually Methane) but that the technology tried to capture all of the resultant CO2 so that none would be released.
"Green" ammonia is the nickname for producing it without any potential greenhouse gas at all. That would be done by using solar power as the energy source rather than methane burning for instance.
Old fashioned dirty ammonia would be formed using some carbon-containing burning source where the producers don't give a damm and just let the CO2 go into the air. This, for instance, is what Saudi Arabia and other producers always did.
3. Saudi wants to improve its reputation as a dirty fuels country and so has partnered with Japan (and others) to use its huge excess of methane oil well burn-off gas in a "blue" CO2 capture technology. Japan is stuck with a gigantic problem, being formerly a coal importer and then a nearly out of control nuke builder. It is desperate to get enough clean energy to get its economy back into world competitive shape.
4. In the larger picture, Ammonia is just a substitute for Hydrogen in anything you've heard about a 21st century "hydrogen economy." Ammonia is a little safer and easier to handle generally (although large amounts of ammonia can wipe out a small town almost as well as a chlorine gas rupture could --- it is a power-laden chemical not to be screwed with.) This gives energy planners pause as to how many citizens to trust using raw ammonia resources in their homes or vehicles for instance. Japan plans to use this firstly as a powerplant supplement (less than 1% of feedstock) and, apparently some transportation concepts. The Netherlands uses "green" ammonia in some technologies --- the end use technologies should be the same regardless of colored nickname.
5. Our country could produce huge amounts of either "color", but especially "blue" if we wanted to. Why? The don't give a sh!t frackers of North Dakota are flaring off so much "waste" methane that you can literally see it from space, brighter than the Twin Cities.
We've still got a LONG way to go. ... even in this country.
