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unicellular :-
- singled celled living creature who performs and maintain their life needs and services by performing various types of jobs 
- it wants protection 
- having short-lived or abridged life length 
- organelles are in best and flawless optimum numbers .
- it increases size and having limitation on command of nucleus .

multicellular :-
- they posses various functions at a time
- cells builds their own era and parts and they are having special skill of  moving
- they form tissues by joining various commands of cells 
- some are short-lived and some are big-lived
- total command of nucleus .
- elongated cells 
- having single and special skill of functioning .

kernplasma ration is responsible for the  shape and various elements like range of command and control of the structure , amount of metabolic functioning with their availability of space and surface and those which are multicellular organism depend on their cells that how much they constitutes , some are small and some microns e.g. PPLO is smallest one and ostrich's egg considered as biggest cell prokaryotes ( 1 - 10 micro m) eukaryotes ( 10 - 100) micro m .