Unicellular organisms are organisms that have 1 cell that make up its body. Bacteria, Amoeba, protozoa, viruses, diatoms are the five different types of unicellular organisms. There are conflicts on the number of single celled organisms in the world because all of them have not been discovered yet.
There are many types of organisms that belong to the Monera Kingdom. All of them are unicellular organisms, this is, that are formed by a single cell. Examples of them are green and blue algae and several types of bacteria.
Multicellular organisms are made up of many cells. Unicellular organisms are made of one cell. Multicellular organisms are Eukaryote in nature. Unicellular organisms are prokayotic in nature. Unicellular are microscopic in nature. Multicellular are macroscopic in nature.