Final answer:
The cell wall structure is the best characteristic that distinguishes Archaebacteria from Eubacteria.
Step-by-step explanation:
The best characteristic that distinguishes the kingdom Archaebacteria from the kingdom Eubacteria is the cell wall structure. Archaebacteria have a unique cell wall composition that is different from Eubacteria. Archaebacteria have a cell wall made up of pseudomurein, while Eubacteria have a cell wall made up of peptidoglycan.
Learn more about distinguishing characteristics of Archaebacteria and Eubacteria