These two ingredients share a few similarities. They are derived from dairy, and both are very effective in promoting muscle hypertrophy. They are also very different and can be used in their own way. Whey Protein Concentrate (WPC) contains minimal lactose, fat, and cholesterol with it being 29% to 89% pure protein. A little lactose, fat, and cholesterol can be a good thing if you are not looking to “cut up”, as these will also aid in muscle growth. Whey Protein Isolate (WPI) is a purer form of protein, being anywhere from 90%+ useable protein. There is almost no lactose, fat, or cholesterol in WPI. WPI is very beneficial and effective when looking to take your fat loss to the extreme, eliminating any by products and nutrients that may make loosing that last bit of fat difficult. WPI can also be a suitable choice for someone who may not be able to consume WPC due to the lactose in it. In most cases individuals who are lactose intolerant find WPI to be a very effective replacement. In summary, WPC is a great choice when trying to promote muscle hypertorhphy while not being too concerned about extreme fat loss, whereas WPI would be a better choice (still promoting muscle growth) when trying to really burn fat and are already doing everything else to do so (diet, cardio, etc.). We also have a great article you can reference on Whey Protein Isolates by following the link below: