OWIN oAuth中的ValidateClientAuthentication方法和GrantResourceOwnerCredentials方法有什么区别?

I am beginner to oauth and owin in .NET. I was trying to understand these methods ValidateClientAuthentication method and GrantResourceOwnerCredentials method. I understood that GrantResourceOwnerCredentials method can be used to validate credentials and generate token. Then, what is the purpose the method ValidateClientAuthentication(). kindly guide me regarding this. Thanks a lot.I am beginner to oauth and owin in .NET. I was