Asthma and chronic obstructive pulmonary disease (COPD) are prevalent respiratory conditions with overlapping disease characteristics. Differentiation between asthma and COPD is important because several aspects of the guideline-recommended management strategies differ for these conditions. This review identifies the epidemiologic, etiologic, and clinical distinctions of these diseases to assist physicians and other clinicians in differentiating between asthma and COPD. Key components of the guideline-recommended management approaches for these conditions are also reviewed.Relevant articles were found by searching the MEDLINE database for "asthma" and "chronic obstructive pulmonary disease OR COPD" in association with the terms "diagnostic criteria" and "differential diagnosis". Recent statistical summaries (meta-analyses), reviews, and consensus-type documents were also included.A review of relevant articles found that, although asthma and COPD may occur simultaneously, differences between these diseases are frequently recognized in terms of age at onset, prevalence in relation to age and sex, potential for reversibility of airway obstruction, pathophysiology, and typical symptom presentation. A thorough clinical history in conjunction with lung function testing usually aids in diagnostic distinction and choice of therapeutic interventions. Radiologic imaging and inflammatory marker testing may also aid in the differentiation of these conditions. Over time, disease progression often differs between asthma and COPD.Although overlaps exist in the disease characteristics of asthma and COPD, careful history, physical examination, and lung function testing often reveal information that facilitates distinction between these diseases, allowing physicians and other clinicians to better tailor their therapy.