What is the difference between SOAP and REST API in Salesforce?

REST Api-

REST is basically an architectural style of the web services that work as a channel of communication between different computers or systems on the internet. The term REST API is something else.

Those application programming interfaces that are backed by the architectural style of REST architectural system are called REST APIs. REST API compliant web services, database systems, and computer systems permit requesting systems to get robust access and redefine representations of web based resources by deploying a predefined set of stateless protocols and standard operations.

SOAP Api-

SOAP is a standard communication protocol system that permits processes using different operating systems like Linux and Windows to communicate via HTTP and its XML. SOAP based APIs are designed to create, recover, update and delete records like accounts, passwords, leads, and custom objects.

These offers over twenty different kinds of calls that make it easy for the API developers to maintain their accounts, perform accurate searches and much more. These can then be used with all those languages that support web services.