The main focus point for these comparisons Is homeostasis which in its simplest form is the body or cell adjusting to best fit survival or balance. With that both organisms will be from different group one consisting of a unicellular and the other multicellular
Diatom
Unicellular organisms are known to exert tight control over their cell size with a Diatom its from the rigid silica that impose on the cell wall that keeps it tight.These photosynthetic eukaryotes are known to be responsible for about 20% of global photosynthesis, and maintains homeostasis with the biosynthesis and turnover of storage lipids.
Human
Unlike the unicellular organisms of course multicellular organisms have multiple cells and some times don’t have a cell wall at all.the primary components of homeostasis
Stimulus: A stimulus from a change in the environment kicks something out of balance in the body.
Receptor: The receptor reacts to the change by informing the control unit.
Control unit: The control unit then communicates the change needed to bring the body back into balance.
Effector: The effector receives this information and acts on the change that is needed.
“To maintain homeostasis, unicellular organisms grow, respond to the environment, transform energy, and reproduce. The cells of multicellular organisms become specialized for particular tasks and communicate with one another to maintain homeostasis.”