The normal shock is at 90 degrees angle to the incoming flow and the flow behind it will always be subsonic and it gives large total pressure loss whereas the oblique shock is at some angle to the incoming flow and only the normal component of flow velocity and tangential component of flow velocity remains unchanged the lesser the angel of oblique the lower the total pressure loss. Flow may or may not be subsonic after passing through oblique shock depending upon upstream Mach.
In normal shock flow velocity direction doesn't change while in oblique shock flow turns towards the oblique shock direction.