Both bacteria and viruses cause disease. Bacteria have the quality to divide very quickly and cause common infections like boils and acne.
Viruses are much smaller and attack an infected cell producing millions of viruses. They cause many common diseases like cold and influenza.
Below Virus and Bacteria info from Wikipedia (Read More):-
A virus (from the Latin virus meaning toxin or poison) is a microscopic infectious agent that can reproduce only inside a host cell. Viruses infect all types of organisms: from animals and plants, to bacteria and archaea.[1] Since the initial discovery of tobacco mosaic virus by Martinus Beijerinck in 1898,[2] more than 5,000 types of virus have been described in detail,[3] although most types of virus remain undiscovered.[4] Viruses are ubiquitous, as they are found in almost every ecosystem on Earth,[5] and are the most abundant type of biological entity on the planet.[6] The study of viruses is known as virology, and is a branch of microbiology.
http://en.wikipedia.org/wiki/Virus
The bacteria (en-us-bacteria.ogg [bækˈtɪərɪə] (help·info); singular: bacterium)[α] are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals. Bacteria are ubiquitous in every habitat on Earth, growing in soil, acidic hot springs, radioactive waste,[2] water, and deep in the Earth's crust, as well as in organic matter and the live bodies of plants and animals. There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water; in all, there are approximately five nonillion (5×1030) bacteria on Earth,[3] forming much of the world's biomass.[4] Bacteria are vital in recycling nutrients, with many steps in nutrient cycles depending on these organisms, such as the fixation of nitrogen from the atmosphere and putrefaction. However, most bacteria have not been characterized, and only about half of the phyla of bacteria have species that can be grown in the laboratory.[5] The study of bacteria is known as bacteriology, a branch of microbiology.
http://en.wikipedia.org/wiki/Bacteria
