Archaebacteria vs Eubacteria. In the past, archaea were classified as bacteria and were called archaebacteria.
But it was discovered that archaea have a distinct evolutionary history and biochemistry compared with bacteria. The similarities are that archaea and eubacteria are single-celled organisms that do not have a nucleus or organelles. edit Size and shape. Human Microbiome Project. Bonnie Bassler on how bacteria "talk".