I found this:
The amount of protein recorded on food labels only lists the complete proteins.
The proteins counted in Nutrition Facts are those made with essential
amino acids. Rice and lentils independently, for example, are high in protein (and if you buy them pre-packaged with their Nutrition Facts on the label, you'll see the high amount of protein), but neither is made up of "complete" protein, meaning *all* the essential amino acids the human body needs. That's the difference.
You'll find that by using the somewhat cryptic but functional USDA online database (link below) that you can do a nutrient search for just about any general food item and the nutrients, including protein broken out into its respective essential amino acids for that food (down to the thousandths of a gram):