The definition of spaces as "safe" or "comfortable" is subjective, there may be some who use the terms synonymously but I don't. There are safe spaces for drug addicts to discuss their experiences of addiction with each other; these spaces frequently deal with extremely uncomfortable topics. They are "safe" in that there are a few precepts that must be agreed upon in order to enter into the conversation, e.g. "There are no leaders; we are all peers" or "No drug addict is unworthy of help" or "Programs or methodologies that demand exclusivity are vulnerable to cultism and their promotion is not permitted here" etc. The idea is to make certain baseline topics axiomatic so the group can focus their conversations more productively than endlessly rehashing the same topic over and over again, which can exhaust and overwhelm members, to the detriment of all. That definition of safety is created by the community and agreed to by its members, and every safe space is free to define safety differently.