Conventional ammonia (gray ammonia):

• Hydrogen is produced from fossil fuels such as natural gas or coal.
• The production process generates large amounts of CO₂ and is a major source of industrial carbon emissions.

Green ammonia:

• Hydrogen comes from water electrolysis powered by renewable energy such as wind or solar power.
• The production process results in virtually no carbon emissions and is recognized globally as a low-carbon nitrogen product.

Essential difference: They share the same uses, but differ fundamentally in carbon-emission sources and environmental impact—the environmental value is completely different.