Cell

The basic difference is in their sizes. the organ and the organelle essentially perform the same the same function , though on different level.
Organs are found in the bodies of multicellular organisms in which the organ does a specific function. the organ is also multicellular.
On the other hand , organelles are substances found in individual cells, which perform an important and specific function.Essentially what an organ is to a multicellular organism, an organelle is to an individual cell.for example, lungs help in respiration of humans. the same function is done by the mitochondria in the cells