What's the difference? A revolutionary thinks past the immediate, imagining a future that doesn't necessarily depend 1-to-1 on the past or present, respond directly to it. A reactionary, on the other hand, responds to the challenges they see or experience. Surrealism was revolutionary in that it allowed thinkers to break away from 'reality' through various methods (automatic writing, for instance) that, at least in theory, let them imagine the real as completely different. Surrealism responded to contemporary challenges, but their thought, ideally, wasn't limited by such basic questions like "What should we do?"
For questions of ecology, this means thinking less about how to respond to challenges like getting businesses on board with mitigation and adaptation initiatives and instead thinking about how to change the system completely, making those issues irrelevant.
Environmentalism and sustainability are reactionary. Ecology, on the other hand, can be revolutionary, but to be ecological, we have to look past contested notions of nature and the environment and re-evaluate the way we treat broader issues of labor, markets, consumption and the commodity form. Workers, for example, should have more vacation, more protection, and higher wages. Sure, this correlates to higher prices of goods and services, but it makes sense that the more leisure time people have, the less stuff they'd need to consume, focusing instead on their time spent with family and friends. It would also force us to reconsider what can and can't be commoditized, questioning the economic rationality of markets that demands the commodification of non-commodities (like environmental quality) whose marketization only serves to dispossess the public of their physical and emotional benefits.