Cells are the basic units of life. They can exist by themselves, like bacteria, or apart of a larger organism, like our cells. Viruses are non-living infectious particles that are much smaller then a cell, and need a living host to reproduce. They cannot reproduce outside of a living host cell, nor can they be seen without an electron microscope.
The viruses are the submicroscopic infectious agent. The viruses have RNA or DNA as their genetic material covered with the proteinaceous capsid. They do not have their replication machinery hence they are unable to reproduce without the host cell. They are considered as non living without the host cell. It can infect the host cells and reproduce with the utilisation of cellular machinery and energy. The viruses do not have to maintain homeostasis. Hence they are considered as the connecting link between the living and non living world.
In the living cells the genetic material is DNA only not RNA. The living cells have their own cellular machinery to multiply and growth. Hence they are self reproducible. They can metabolise to produce and consume energy. The living cells can also maintain homeostasis.
