Can anyone provide some insight on this?
Is this question about animal protein vs plant-based protein? In general, animal proteins like meat, fish, dairy and eggs contain all the 9 essential amino acids (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine). Plant-based proteins from foods like beans, grains, nuts, and soy are rich in some amino acids but may lack others. A well-balanced diet with a variety of foods can provide sufficient protein for the body’s needs.
TL;DR Animal foods are the highest quality protein / amino acid sources. Plant sources lack one or more amino acids, which makes it more difficult to get all the amino acids that your body needs.