Future Trading and salam contracts

AOA,
My question is related to future trading and Salam contracts, I have been going through the research for a long time. As it is said that we are not allowed to make forward contracts in Islam but if we read the Salam contracts it says that forward contracts are allowed if they are properly written or agreed by the buyer and seller, so does this not make this factor halal? as the contract is defined clearly between the exchange and client?
Looking forward to your response
Kind regards
Abdul Fatir