Green transformation is an effective way for supply chains to achieve sustainable development. In the heterogeneous substitute product coexistence environment, it is valuable to explore the motivation behind CSR implementation as well as the advantages and differences associated with different members’ CSR implementations. In this study, we consider that the manufacturer produces both green products and ordinary products that are substitutes for each other and construct a CSR-absence scenario (Model N), a retailer implementing CSR scenario (Model R), and a manufacturer implementing CSR scenario (Model M). Applying a game-theory-based method, we obtain the optimal pricing, green decision, and supply chain profit under different scenarios. We analyze the effects of consumers’ green preference, green product function coefficient, and CSR level on decision making and performance. Through comparison and numerical analysis, we find the following: (1) Although the CSR behaviors of the manufacturer and the retailer squeeze the market demand space of the ordinary products, the greenness of the green product increases, and the retail price decreases. This not only enhances the consumer surplus of green products but also increases the profit and social welfare of the supply chain system. (2) The eco-friendliness of green products, product demand, and social welfare levels are the highest when the retailer implements CSR, followed by when the manufacturer implements CSR, and are the lowest in the CSR-absence scenario. In addition, the following retailer can enhance both its and the manufacturer’s profits through implementing CSR within a reasonable range. (3) The numerical analysis results show that, when the functional attributes of the green products meet a certain level, supply chain members implementing CSR does not affect consumers’ choice of green products.