Many studies have recognized that individual variability shapes user experience in virtual reality (VR), yet little is known about how these differences influence objective cognitive engagement and performance outcomes. This study investigates how cognitive factors (IQ, age) and technological familiarity (tech enthusiasm, tech fluency, first-time VR experience) influence EEG-derived cognitive responses (alpha and theta activity) and task performance (trial duration) during VR interactions. Sixteen autistic and sixteen neurotypical participants engaged with various VR interactions while their neural activity was recorded using a Muse S EEG. Correlational analyses showed distinct group-specific patterns: higher IQ correlated with elevated average alpha and theta power in autistic participants, while tech fluency significantly influenced performance outcomes only in neurotypical group. Prior VR experience correlated with better performance in the neurotypical group but slower adaptation in the autistic group. These results highlight the role of individual variability in shaping VR engagement and underscore the importance of personalized design approaches. This work provides foundational insights toward advancing inclusive, user-centered VR systems. © 2025 by the authors.