Quality of life (Qol) results from a complex interplay of physical, mental, and social aspects. Traditional assessments of Qol may not adequately describe well-being in serious chronic illness such as in people with Parkinson's disease (PwPD). This cross-sectional observational study explores differences and similarities of assessment through Health-Related Qol (HRQoL) versus individual Qol, measured as Schedule for the Evaluation of Individual Qol (SEIQoL), and analyzes the relative contributions of the most common psychological difficulties (anxiety, depression, apathy) in Parkinson's disease. 48 PwPD (mean age: 67 years; IQR: 60.25-72.75; 12 women) completed SEIQoL and Parkinson's Disease Questionnaires (PDQ-39) for HRQoL. In addition, measures for anxiety, depression, apathy, cognitive function, daytime sleepiness, and motor performance were obtained. Multiple linear regression was performed with both QoL summary indices as dependent variables. Interestingly, HRQoL and SEIQoL were not correlated to each other. Of all psychological difficulties only anxiety was a significant predictor of HRQoL and only self-rated apathy was a significant predictor of SEIQoL. High daytime sleepiness and medication doses were associated with lower HRQoL. In contrast, SEIQoL showed that family, relationships, autonomy and health were the most important domains, with health satisfaction being lowest. HRQoL and SEIQoL measure different aspects of QoL. Therefore, in future research studies both should be used together for an adequate assessment of therapies and effective rehabilitation strategies to ease the burden for PwPD.