The size of the messages that can be received on the wire by services using the BasicHttpBinding is bounded by the amount of memory allocated for each message. This bound on message size is intended to limit exposure to DoS-style attacks.
For buffered transports, (TransferMode set to Buffered). This value is always equal to that specified by the MaxReceivedMessageSize.
For streamed transports (TransferMode set to Streamed), only the SOAP headers must be buffered to generate the message. The body can be streamed in on-demand. In this case, MaxBufferSize is less than or equal to MaxReceivedMessageSize, where MaxReceivedMessageSize bounds the size of the overall message (headers and body) and MaxBufferSize bounds the size of the SOAP headers.