Bacteria and archaea both share the fact that they are single-celled prokaryotic microorganisms that lack membrane enclosed nuclei. It has been discovered that the two typically can be found to have the same size and shape as one another. “They are both found occurring as rods, cocci, spirals, plates, coiled etc.” ("Archaea vs. Bacteria," n.d.). Both organisms use the flagella to swim and also reproduce by means of binary fission. On the surface these similarities can make it difficult to tell the difference between archaea and bacteria. ("Archaea vs. Bacteria," n.d.).
When comparing bacteria and archaea you will begin to notice that their similarities pale in comparison to the differences they have, they truly represent two very different classifications. “In fact, archaea differ from bacteria as much as humans do, in terms of their biochemistry and genetic structure” ("What Are the Differences," n.d.). The environment in which the two can be found can differ greatly as well. A type of archaea known as thermophiles can survive at temperatures as high as 100 degrees Celsius or halophiles which can be found in extreme harsh conditions that would not be ideal for the survival of bacteria, like the Dead Sea or that of the Great Salt Lake where the salinity levels have been measured up to 8 times greater than that of the ocean ("Physical Characteristics of Great," n.d.). When examining the cell membrane you can see the archaea begin to differ in that their cell wall does not contain peptidoglycan like what is found in bacteria cell walls. Their cells instead are found to have pseudopeptidoglycan. ("What Are the Differences," n.d.).
The cell membranes of archaea reveal more differences as they are unique and have different Ribosomal RNAs. Archaea have three RNA polymerases more similar to eukaryotes, whereas, bacteria only have one RNA polymerase. Bacteria and archaea both have lipids but the lipids in bacteria contain fatty acids with
References: Archaea vs. Bacteria. (n.d.). Retrieved February 17, 2015, from http://www.diffen.com/difference/Archaea_vs_Bacteria Difference between Archaea and Bacteria. (n.d.). Retrieved February 17, 2015, from http://www.differencebetween.net/science/difference-between-archaea-and-bacteria / Physical characteristics of Great Salt Lake. (n.d.). Retrieved February 17, 2015, from http://learn.genetics.utah.edu/content/gsl/physical_char/ What are the differences between Archaea and Bacteria? (n.d.). Retrieved February 17, 2015, from http://www.wisegeek.org/what-are-the-differences-between-archaea-and-bacteria.htm