Typical bacteria are the most common types of bacteria that are found in the environment. These bacteria are typically non-pathogenic, meaning they do not cause harm to humans or other organisms. They are usually classified as Gram positive or Gram negative based on their cell wall composition and are found in a wide variety of habitats.
Atypical bacteria, on the other hand, are bacteria that have certain traits that make them different from typical bacteria. These bacteria can be either Gram positive or Gram negative, but have certain features which set them apart from the other types. Some examples of atypical bacteria are the acid-fast bacilli, spirochetes, and actinomycetes. These bacteria are often more difficult to study, because they are not as common as typical bacteria.
Atypical bacteria can also be more dangerous than typical bacteria, as some of them are pathogenic and can cause diseases. Examples of atypical bacteria that are pathogenic include Mycobacterium tuberculosis, which causes tuberculosis, and Yersinia pestis, which is responsible for the plague. In addition, some atypical bacteria can cause antibiotic resistance, meaning they can survive in environments that would normally not be able to support other types of bacteria.
Overall, the main difference between typical and atypical bacteria is that typical bacteria are more common and usually non-pathogenic, while atypical bacteria are less common and can be pathogenic.