Why did people think that archae and bacteria are the same

Archae have more complex RNA polymerases than bacteria, smaller 2 Eucarya. unlike bacteria, Archae cell walls do not certain peptidoglycan. archae had different membrane lipid bonding from bacteria and eukarya. they are genetic diseases. in the past archae was classified as a bacteria and was called archeabacteria. but it was discovered that archae have a distinct evolutionary history and biochemistry compared with bacteria. the similarities are that Archae and eubacteria are prokaryotes single cell organisms that do not have a nucleus or organellas