Describe how bacteria are different from archaea.

Similar:

Members of Bacteria and Archaea are prokaryotes: single-celled organisms lacking true nuclei and other membrane-enclosed organelles. 

Different:

Bacteria and archaea differ in cell wall characteristics and membrane lipid composition. They also differ in RNA polymerase structure and protein synthesis.

Archaea:

Many extremophiles fall within the Archaea. Some archaea, the extreme halophiles (salt lovers), tolerate salt concentrations as high as nearly ten times that of seawater. Some Archaea have been found in environments not considered extreme

Bacteria:

Some bacteria grow at temperatures above 80° C.