Whey is the clear liquid drained off milk during the making of cheese. It contains protein and all 8 essential amino acids are present, but not in sufficient quantity to be a sole source of protein unless you plan to eat over 2 cups or 133 grams per day. None the less whey (acid or sweet) is a complete protein.
Amino acid pills vary a lot and it depends on the source and structure of the protein. Gelatin and corn contain protein but are incomplete sources because they don’t contain all 8 essential amino acids. Egg whites contain the ideal proportion and content of amino acids. However raw egg whites contain avidin, which destroys another nutrient biotin also in egg white.
Essential amino acids are the building blocks of protein structures (muscles, organs, and cells), in man and animals. You should find out what the source of protein is from the label or package insert and whether the pills contain all 8 essential amino acids and in sufficient amounts.
Essential amino acids for adults and their RDA (Recommended Dietary Allowance 1989) are: isoleucine (10 milligrams); leucine (14 milligrams); lysine (12 milligrams); methionine (13 milligrams); phenylalanine (14 milligrams); threonine (7 milligrams); tryptophan (3.5 milligrams); valine (10 milligrams). Infants also need histidine (28 milligrams). These amounts are per kilogram of body weight per day.
Take your body weight and divide by 2.2 to get your weight in kilograms. Next, multiply each amino acid in milligrams by your weight in kilograms. For instance, if your weight was 169 pounds divided by 2.2, your weight in kilograms is 77. Next, multiply 10 milligrams of isoleucine times 77. Your RDA for isoleucine is 770 milligrams per day. This would include isoleucine from all food sources of protein in a day.
Don’t overdo consuming protein as food, supplements or pills.