SOAP vs REST Web APIs

Have started working on some integration pieces and it required clarity on the standards to be used. From the little research that I have done below is the understanding. For any interaction to happen between applications we need to have a handshake at two levels :- 

1.  The protocol to be used to exchange the data packets. 
2.  The format in which the data packets will be exchanged. 

The two popular standards that are used to access Web services (APIs) over http are 

SOAP: 

This is a full protocol. Its like an envelop which is added on top of the message. Because SOAP is an envelope the messages need to be packed and unpacked to and from the enveloped. The message is however formatted in XML. 

REST: 

Rest does not directly compare to SOAP as its not a protocol. Its like a postcard which is open and it is transferred over http protocol. Thus making it light and faster however less secure. The messages in REST standard are formatted as JSON. 

Primary Use:

Primarily REST API are created for CRUD operations on data (tables) over internet. REST is focused on accessing named resources through a single consistent interface.

SOAP  focuses on exposing pieces of application logic (not data) as services. SOAP exposes operations. SOAP is focused on accessing named operations, each implement some business logic through different interfaces.

OData: 

Odata is an implementation of REST APIs in a standard that further simplifies/ standardizes the process of handling the request and response headers, status codes, HTTP methods, URL conventions, media types, payload formats, query options, etc. when working with REST API calls.  

WSDL:

WSDL is often used in combination with SOAP service. WSDL defines the service for the consumer and acts as a standard between the consumer and the provider.  It describes how to access a web service and what operations it will perform. A client program connecting to a web service can read the WSDL to determine what functions are available on the server this is also release to the developers to develop the interface with the service and enabling intellisense.