Collagen is going through a popularity stage, sometimes supplements can be like this. You might have heard of Gelatin? Gelatin is a form of Collagen that's been around for many years in the background. Supplement companies have brought Collagen to life, marketing it as an answer for many different things, and sometimes to help with exercise recovery. Because Collagen is made up of amino acids (although a limited range), it is considered to be a type of protein powder.
Collagen supplements come from 2 main sources, Bovine (from cow hooves, cow connective tissues, and cow hides/skins), or Marine (from fish scales and fish). Alternatively, another source of Collagen is Porcine, (from pigs). The Collagen protein sourced from cows (and pigs) is low cost, much cheaper than other types of protein sources, like Whey protein. Supplement companies make bigger profits from using lower cost Bovine Collagen in their formulations. This is a main reason it's pushed so heavily as a cure all. Marine Collagen is the more costly form of Collagen to source and produce.
Bovine Collagen may be of help to support specifically connective tissue (ligaments and tendons). Marine Collagen may be of help for all around Collagen support - support for skin, hair, and nails, as well as connective tissue, and the gut.
Collagen is not suited for supporting lean muscle or for helping muscles recover from exercise. This is because Collagen is an incomplete protein, containing a limited range of amino acids (containing mainly Glycine). For muscle recovery and repair the amino acids that may help support the most are called the BCAAs (branched chain amino acids). Muscles are mainly made up of the BCAAs. BCAAs are found in very high amounts in meat, and dairy proteins like Whey protein, but they are only contained in very small amounts in Collagen.
Because Collagen doesn't contain the BCAAs levels needed, for recovery from exercise, Whey protein powder is the best option for that purpose, or Casein protein powder (which like Whey comes from milk). Pea protein is also high in BCAAs, but generally many people feel Whey and Casein do a better job at supporting their lean muscle. Whey also contains abundant levels of amino acids and natural properties that may help support immunity. Grass Fed NZ Whey also contains a healthy fat called CLA which may also help contribute to health, muscle development, and helping stay leaner. Benefits of Collagen supplements are much narrower, they are limited to the levels of amino acids that it contains.
I take Marine Collagen to help support my joints, tendons and ligaments, as well as gut and skin health. I take it before bed, for me the high Glycine amounts helps with deeper sleep. For exercise and muscle recovery, and for health, I always use Whey Protein. It supports my recovery well, and may help offer high immune and health support. I don't take Collagen post workout, or for muscle recovery purposes. Research shows Collagen interferes with protein efficiency of high quality protein – it may reduce the bodies ability to use the amino acids needed at this time, and recovery may not be optimum. Some supplement companies do add Collagen to post workout shakes, but it may not be a good way to go, unless the goal is connective tissue support, and not lean muscle support.