Purpose: To compare patient characteristics, upper airway (UA) collapse patterns and treatment outcome in obstructive sleep apnea (OSA) patients, including non-positional OSA patients (NPP) and positional OSA patients (PP), and non-OSA. Methods: Cohort study of patients screened for OSA in 2012. Polysomnography was performed and UA was evaluated using the VOTE classification during drug-induced sleep endoscopy (DISE). Treatment outcome of MAD and UA surgery was evaluated. Results: Eight hundred sixty patients were included. Higher BMI, larger neck circumference, and greater age were independent significant predictors for OSA. DISE was performed in 543 patients: 119 non-OSA and 424 OSA patients of whom 257 PP and 167 NPP patients. PP were younger, had smaller neck circumference, lower BMI and apnea-hypopnea index (AHI) than NPP. Collapse at velum (p < 0.001) and oropharynx (p < 0.001) significantly increased the odds for having OSA. Tongue base and epiglottis collapse were, on group level, not determinative for OSA or non-OSA. Complete concentric collapse (CCC) was observed less frequently in PP (31.5%) as compared to NPP (46.1%). After UA surgery, OSA often was cured or improved to less severe positional OSA. Lower efficacy of UA surgery was observed in PP as compared to NPP. No differences were observed in MAD treatment outcome. Conclusions: Current study provides insight in patients screened for OSA: collapse at velum and oropharynx significantly determined presence of OSA and CCC occurred less frequently in PP compared to NPP. In addition, residual positional dependency is common after UA surgery. More trials are needed to gain insight in pathophysiology and treatment outcome.