Technical design review is a product development activity whose goal is to inspect a design concerning its technical characteristics. Nowadays, designs are often presented as 3D CAD virtual models with visualization being the essential way of interacting with it. Conventional technologies present a virtual environment on the monitor screen, which is limited in presenting a 3D model as a 2D representation. Its limitation affects users' spatial understanding, causing difficulties in space depth comprehension and requiring developed spatial visualization skills. Stereoscopy and multimodality of Virtual Reality technology enable the user to interact with a 3D virtual model inside the virtual environment, demining cognitive load needed for visual perception of spatial information and focusing users' attention to design review and design understanding, necessary for its efficiency. Conceptual design review experiment study has been conducted to investigate differences in design understanding when it is presented in an immersive virtual environment by Virtual Reality and in a non-immersive virtual environment by conventional technology (monitor screen, keyboard, and mouse). Design understanding in this study refers to mechanisms understanding, spatial understanding of dimensions and design errors detection. Data is collected by asking participants to fill out a prior experience questionnaire, Presence Questionnaire, Mental Rotations Test, and provide the researcher with verbal answers during design review and while answering confidence questions. Statistical analysis results have shown that error in dimensions assessment is significantly lower in an immersive virtual environment, leading to the assumption that immersion of virtual environment has a positive effect on dimensions assessment and spatial comprehension. On the other hand, the immersive virtual environment did not provide participants with better design understanding when it comes to design errors detection or mechanisms understanding.