How are unicellular and multi cellular organisms alike/how are they different

Unicellular organisms contain one cell and all of their functions are based on that one cell whereas multi-cellular organisms contain more than one cell and there functions are divided amongst different cells like nervous cells, cardiac muscle cells etc. 

Multi-cellular organisms can be much larger and more complex. This is because the cells of theorganism have specialized into many different types of cells such as nerve cells, blood cells, muscle cells all performing different functions.

Instruments such as gravimeters and magnetometers are used.