Vegan protein, in general, are not ‘full’ proteins, as in they do not contain all essential amino acids which are used as building blocks for much of the tissues in our body, including muscle. Eggs, milk and meats are sources of complete proteins, however so is Soya and vegan EAAs (essential amino acids) can be supplemented into your diet.
Another difference is that vegan protein has been found to be less ‘bio-available’, which means that say we consume 20g of soy protein, only 12g will end up being available for the body to use. 20g of whey protein, on the other hand, will provide 18g of protein that can be digested, processed and available to be used for protein synthesis.
Another thing is that some vegan proteins are more environmentally friendly per gram of protein than animal ones. For example, cows require more land and produce more greenhouse gases than soya beans. However, soya beans flown from abroad have a higher carbon footprint than beef or milk from your home country.
Some studies have shown that vegan protein sources are more beneficial for health and also your gut microbiome. But these are often found to be more complex issues than just the type of protein. A diet rich in vegetables and fibre will be beneficial for gut health because of the presence of those, not necessarily the source of the protein.
So that one is a little up in the air, but for most people without allergies or specific medical dietary requirements, a diet mixed of lean animal proteins, different carb sources, plenty of fruit and veg, and good levels of dietary protein, will be optimal for gut health.
There are plenty of successful world tour cyclists who follow vegan diets, and many equally successful riders who follow non-vegan diets. Choose what works for you, what matches your ethics and environmental/sustainability views, and what you want to do. Both can work very effectively.