UDP packet processing is faster compared to TCP packet processing. This is because once TCP packets are delivered to the destination, an acknowledgement is expected at the transmission end. If no acknowledgement is received, re-transmission of packets occurs at the transmission end. This is opposite to UDP operation, in which no acknowledgement is necessary.

TCP is a reliable protocol that utilizes windowing and acknowledgement packets to ensure all traffic is transmitted and received UDP is an unreliable protocol that does not utilize windowing and acknowledgements, and is good to use when you can't re-transmit a packet (EG a voice or video packet)

UDP is for like Skype and TCP is for like Youtube.....thats all I know but it has to do with the way packets are received and acknowledged