They are the same in theory, even though their origination is different. The issue comes when P2P sells tokens early before the ICO is even over. It creates issues with the white paper where the token creation has limits. Essentially they are operating outside of the jurisdiction of the ventures themselves, selling someone elses stock/token without consent.
You are clearly confused. P2P exchanges allow to sell developed tokens peer-to-peer. The price of a token at the time of a sale on p2p is only decided by what price one is willing to pay for it meeting what another one is willing to sell it for and does NOT constitute the true value of a token. Once a token is listed on public exchange, sales value of much larger group of investors will decide what true current value of a token is..