Magento supports both SOAP (short for Simple Object Access Protocol) and REST (short for Representational State Transfer) types of communication with the Web API. Authentication methods themselves are not really bound to any of them. We can use the same authentication method and Web API method calls with both SOAP and REST.
Some of the REST specifics we might outline as follows:
HTTPheader requires an authorization parameter, specifying the authentication token with the Bearer HTTP authorization scheme,
Authorization: Bearer <TOKEN>.
<TOKEN>is the authentication token returned by the Magento token service. ...