Carbon neutrality requires joint efforts of society. Consumer subsidies are an important way to spread the concept of green consumption. Point-based green consumption reward programs, which are being piloted in many cities, represent a greenness subsidy scheme. Under this new subsidy scheme, the amount of subsidy is calculated based on the greenness of the product consumed—The greener the product is, the higher the subsidy. This is different from the traditional lump-sum subsidy scheme where the government determines the amount of subsidy that is not related to the greenness of the product. This paper constructs a game-theoretic model with endogenized green product development and pricing decisions. It proposes optimal subsidy strategies under lump-sum and greenness subsidy schemes and compares their economic and environmental consequences. The results show that both schemes can encourage firms to exert more efforts in green product development, and greenness subsidy is effective in a wider range of contexts. When optimizing a subsidy scheme, it is important to note that consumer subsidies can increase carbon emissions by stimulating overconsumption; however, a large market size and strong consumer preference for green products can mitigate this adverse effect. From the perspective of scheme selection, when the government budget is extremely low or high, the greenness-based subsidy performs better in terms of carbon reduction. When the budget is moderate, the lump-sum subsidy scheme with a proper subsidy standard can achieve higher emission reduction. These findings provide theoretical support for governments in designing green consumption subsidy schemes.