IP address
An IP address serves two principal functions. It identifies the host, or more specifically its network interface, and it provides the location of the host in the network, and thus the capability of establishing a path to that host. Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there."
The header of each IP packet contains the IP address of the sending host, and that of the destination host.
Address pool
In the context of the Internet addressing structure, an address pool is a set of Internet Protocol addresses available at any level in the IP address allocation hierarchy. At the top level, the IP address pool is managed by the Internet Assigned Numbers Authority (IANA). The total IPv4 address pool contains (2) addresses, while the size of the IPv6 address pool is 2 () addresses.