Their lipid membrane is very different. Their DNA and RNA sequences are very different from Eubacteria. Cell wall is different. Live in extremely salty places. Live in very hot environments.
Some bacteria have extra small pieces of circular DNA called plasmids.
Smile layers serve to attach bacteria to surfaces. Some have flagella for movement. Some make endospores. Conjugation Conjugation is not reproduction. During conjugation one bacterium with a special plasmid transfers some genetic information to another bacterium which does not have this special plasmid.