TCP/IP consists of dozens of different protocols, but only a few are the "main" protocols that define the core operationof the suite. Of these key protocols, two are usually considered the most important. The Internet Protocol (IP) is the primary OSI network layer (layer three) protocol that provides addressing, datagram routing and other functions in an internetwork. The Transmission Control Protocol (TCP) is the primary transport layer (layer four) protocol, and is responsible for connection establishment and management and
reliable data transport between software processes on devices.IP and TCP are important because many of TCP/IP's most critical functions are implemented at layers three and four.

The difference is that TCP is responsible for the data delivery of a packet and IP is responsible for the logical
addressing. In other words, IP obtains the address and TCP guarantees delivery of data to that address.
TCP/IP is a two-way communication between the client and the server and it is a reliable and there is a confirmation regarding reaching the message to the destination. It is like a phone call.
UDP is a one-way communication only between the client and the server and it is not a reliable and there is no confirmation regarding reaching the message to the destination. It is like a postal mail.
The Internet Protocol (IP) is a network-layer (Layer 3) protocol that contains addressing information and some control information that enables packets to be routed but TCP is a protocol which is responsible for relaiable communication between to Computer on the Network or WWW.
IP is connectionless protocol and TCP is connection orianted protocol because it creates virtual circut between hosts before data transfer.