How do unicellular organisms and multicellular organisms compare in meeting their needs to stay alive

They utilize what they have but both are efficient its just that eukaryotic organisms have a better system for surivival and storage than prokaryotic which in contrast needs a lot of sustained energy.

There are differences between Eukaryotic and Prokaryotic cells. This difference is considered to be the most important distinction between groups of organisms. A Prokaryotic cell does not contain a nucleus. It only contains one chromosome and is a single-celled organism. It was the only form of life on earth for millions of years. Examples of a Prokaryotic cell are the different types of bacteria present today. 
A Eukaryotic cell contains a nucleus; more than one chromosome and is typically a multi-celled organism.  Both plant and animal cells are eukaryotic cells.