Cities account for 75% of resource consumption and 80% of CO2 emissions. With rising urbanization, achieving urban sustainability becomes crucial. The Circular Economy (CE) concept has been proposed to reduce resource consumption, although its link to sustainability remains unclear from theoretical and practical perspectives. This paper provides an in-depth comparative analysis of 57 indicator sets used in academia or practice to measure either CE in urban areas or urban sustainability. Indicators were extracted and categorized according to three conceptual frameworks, namely: the STEEP categories, the Sustainable Development Goals, and inductively-created thematic groups. The similarities among the 57 sets were analyzed to derive clusters. Results show that CE represents a subset of urban sustainability, while offering more indicators to assess specific thematic groups (e.g., waste). In the discussion, the value added by targeting a CE rather than sustainability is questioned, and insights are provided to support actors involved in an urban transition to develop well-informed city targets. The results offer theoretical, practical, and methodological contributions, and aid involved actors, especially those leading urban transition agendas, to unravel the conceptual link between CE and sustainability, specifically at the urban scale.