Unicellular (UC) and multicellular (MC) life forms differ in a number of ways.
1) UCs are also called Prokaryotes, MCs are also called Eukaryotes. Examples of UCs are bacteria, while examples of MCs are plants, animals and higher life forms.
2) UCs do not have a nucleus, while MCs do.
3) UC have one chromosome, MCs have more than one chromosome.
4) UCs have no endoplasmic recticulum, microtubule, mitochondria or lysosome; MCs have all of these organelles.
5) UCs have no Golgi apparatus, while MCs do.
6) UCs have no nuclear membrane, while MCs have a nuclear membrane that is selective.
7) UCs have only one flagellum (of submicroscopic dimensions), while MCs have multiple flagella (of microscopic dimensions).
8) UCs are much smaller in size at 1-10 um, while MCs are bigger in size at 10-100 um or more.