I have seen Aircrafts having been assigned a Stand and Gate, So wanted to know whether the stand and gate are same physical location of airport or they are different but have link between them.
An aircraft stand is a place where an aircraft can be parked.
A gate is a designated area inside the terminal building where passengers will assemble and wait prior to boarding. It includes facilities for checking boarding passes, last-minute customer service such as seating changes and so forth.
In the typical setup most passengers meet, each gate serves just one stand located right outside it. But this is not always the case: airports often have remote stands too, and there will be a smaller number of gates from where passengers are bused (or walk across the apron!) to the appropriate stands. Such a gate is not dedicated to a particular aircraft stand.
In the former case, where a stand is served by a dedicated gate, there is little point in distinguishing between the two. They will often (but not always) share one identifying number, and people happily speak about, for example, taxiing to the gate after landing. But for remote stands a distinction needs to be made.