Difference between dhcp and dns?

DHC Protocol is something that is responsible for providing you as "a device", address in the network. This is something that is predominant in a router. Where as DN Systems is what translates any resources in the Web into Internet Protocol addresses.So, to summarize DHCP identifies you in a network, DNS finds the resources on it.

DNS : Dynamic Host Configuration Protocol is a client/server protocol that automatically provides an Internet Protocol (IP) host with its IP address and other related configuration information such as the subnet mask and default gateway.

DNS: The Domain Name System is a hierarchical decentralized naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities.