Is HTTP Basic Authentication and OAuth 2.0 same?

Yes, HTTP Basic Authentication different from OAuth 2.0. However, the Resource Owner Password Credentials Grant utilizes Basic Authentication Scheme within the Authorization Request for the Client's credentials as described with section 4.3.1. Authorization Request and Response

The Resource Owner Password Credentials Grant is typically used to convert legacy systems to OAuth 2.0 and no more secure than Basic Authentication Scheme.

Resource Owner Password Credentials Grant is intended to be used when no other Grant Types are available and ONLY when there is a high degree of trust between the Resource Owner and the OAuth Client .

Yes, they both are different. Http Basic : This is for authentication and user credentials are encoded then passed in HTTP header to the client server. Basic example for HTTP Basic : Just like traditional web application which asked user to provide credentials and these credentials sent to server in HTTP header. Later server utilize those credentials to authenticate the user.

OAuth 2 : This is for authorization, here the client server required authorization of user data(resource owner) from authorization server. Basic example for OAuth 2 : Let say there is a online game application running on a server, the user accessed the application which starts loading into user's browser. Now that application asking grants from user to post data about games on his Facebook account. Here user authorize his that application to access his Facebook posts through OAuth Standard. Refer the internal mechanism https://tools.ietf.org/html/rfc6749

Basic access authentication usage is comparable to OAuth 2.0 Client Credentials Grant Type.

A session can be created using Basic Authentication and services can be accessed using a sessionid in a stateful environment.

But if you do not want to use the session due to session limitations or stateless services, you can use the OAuth 2.0 Client Credentials Grant Type instead, which creates a token instead of session and sessionid. This token provides access to the services.