Here's a breakdown:
* Protozoa are a diverse group of eukaryotic microorganisms.
* Unicellular organisms are organisms consisting of a single cell.
Therefore, all protozoa are unicellular, but not all unicellular organisms are protozoa.
For example, bacteria are unicellular, but they are prokaryotes (lacking a nucleus), while protozoa are eukaryotes (possessing a nucleus).
