This study aims to investigate the interplay and discrepancies between the socially constructed image and the self-constructed image of Chinese youth in cyberspace. Employing a comparative analytics approach based on big data, this research will collect two kinds of textual data: one containing social media posts discussing "youth" on platforms such as Weibo, representing the society's external perspective; and the other comprising user-generated content created by young people themselves, representing their internal perspective. Through data analysis including topic modeling, sentiment analysis, and discourse analysis, this study systematically compare the two datasets across core themes (e.g., "involution" (内卷), "lying flat" (躺平), career, marriage, and identity), affective tendencies, and value systems. The findings will reveal gaps between broad social stereotypes and the more diverse, nuanced narratives of youth themselves. This research seeks to deepen the understanding of the contemporary youth mentality and provide an empirical basis for bridging the intergenerational cognitive gap and fostering effective social dialogue.