The difference is the interval between data stream segments. So, using the example given in the quote below, the size of the rail car will either be a bit or a byte. From the Urban Dictionary: “Time Division Multiplexing – TDM or Time Division Multiplexing is a term used in Cisco. TDM is simply the transmission of information from several different sources using one common channel or signal. After all of the information is recieved it is reconstructed. Depending on whether bits or bytes are used, TDM is called bit-interleaving or byte-interleaving. TDM output can be compared to a train with 32 railroad cars. Each is owned by a different freight company and every day the train leaves with the 32 cars attached. If one of the companies has product to send, the car is loaded. If the company has nothing to send, the car remains empty, but it is still part of the train.