This research, using a comparative and qualitative approach, examines the impact of political structure on the form, discourse, strategies, and level of effectiveness of environmental activism (green activism). The present study examines two distinct governance contexts: An institutionalized context with an open political opportunity structure (case study: the European Union) and a context with highly centralized governance that limits the space for independent civil society (case study: a centralized state). Research findings show that in an institutionalized context, green activism operates in an interactive and multi-voiced ecosystem. In this space, the radical discourse of street social movements, the technocratic discourse of transnational institutions, and the state-building discourse of green parties within the power structure, in a dialectical interaction, constitute the process of "securitization" of the environment And they advance its transformation into a major political priority and provide the possibility of influencing through various institutional, legal, media, and electoral channels. In contrast, in the context of limited activity of associations and public organizations, the institution has led activists towards adaptive strategies It leads to low-risk and non-confrontational. In this model, activism is largely confined to scientific or indigenous acceptance discourse, It focuses on local and objective issues and lacks effective institutional connections to the country's macro-centers of environmental decision-making and governance. As a result, its impact on macro development policies remains limited and cannot be effective in the country's comprehensive sustainable development policies.