What is the difference between single sign on and open ID

Question

As per my understanding OpenID and SSO is all about using a single identity to sign into many sites. so what is difference ?

Answer 1

"Singe Sign On" is a very general term. There are many ways to implement it, OpenID being one such way.

By "SSO" do you mean SAML SSO?

Refer following SO question for the difference between OpenID and SAML SSO:

What is the difference between OpenID and SAML?

Answer 2

The difference between single sign on and the open id is as follows

If there are two sites abc.com and pqr.com and both support the openID than while accessing both the side it prompt the user for the user-name and password which is same for the openID but user has to enter the user-name and password on both the site.

On single sign on the user login on one site say abc.com and when he visit on the pqr.com he don't need to enter the login user-name and password again, he automatically should get login

For more information you can check the following link http://alleged.org.uk/pdc/2007/08/13.html