Both protocols operate at the Transport Layer of the OSI model. TCP is connection-oriented while UDP is connection-less. TCP includes things like error checking and acknowledgements to ensure reliable delivery of packets and data. UDP is more of a continuous stream that assumes error checking and acknowledgement of data is not necessary, it would typically be used for something like video streaming where dropping a packet here and there isnt a big deal, but having to wait for it to be retransmitted would be an issue.