Although these terms have different meanings within the scientific community, and especially among climate researchers, they are often used interchangeably in the common vernacular. When considered in the context of vegetarianism, they are basically identical.
Furthermore, climate change seems to be slightly more popular in North America. I personally have almost tagged questions with climate-change before realizing there was already a global-warming tag.
There are no questions currently carrying the climate-change tag, so this would only affect newly asked questions going forward.