Azithromycin and Roxithromycin are both macrolide antibiotics. The main difference lies in the different antibacterial spectrum, different applications and different adverse reactions. 1. Different antibacterial spectrum: Azithromycin is the second generation of macrolide antibiotics, erythromycin is the first generation of macrolide antibiotics. 2. Different applications: Azithromycin is mainly used to treat acute pharyngitis and acute tonsillitis caused by Streptococcus pyogenes. Roxithromycin is mainly used to assist in the treatment of cough and other pulmonary infections. 3. Different adverse reactions: Azithromycin causes adverse reactions such as indigestion as well as gastrointestinal flatulence. Roxithromycin may cause diarrhea, abdominal pain and other symptoms. Azithromycin and erythromycin are prescription drugs, both need to be used under the guidance of a professional doctor, not private medication to avoid adverse consequences.