What difference will it make on the output between these two circuits?
I think the connection between the negative input of the opamp and the ground is a mistake. If you delete that connection, the opamp has the function of a buffer. V+ and V- are equal, and since the Vout of the opamp is connected to V-, the output is equal to the input voltage. (just like you would have in fig. a)
The difference is that no current is leaking from the middle point of your voltage divider, since an opamp doesn't draw current on its input.