I feel like social justice movements at large should make more of an effort to distinguish safe spaces from activism and education spaces. They serve different purposes, have different needs, and need different rules. People may be confusing and oversimplifying them.

Yes and no. I think the main mistake people make with safe spaces are:

• Believing that there is such a thing as a safe space when in fact there are only safer spaces. 
• Believing that what makes a space safer is removing demographic groups from it. 

In reality, removing all men from a women’s safe space may make that place safer because there will be less sexism and sexist violence there, but there will still be ableism, transphobia, racism, etc. It is only significantly safer for people whose only problem is sexism, in other words: ablebodied, cisgender, straight, middle class, neurotypical white women. 

What effectively makes a space

safer

is a clear policy against sexism, ableism, transphobia, racism, etc. and a good strategy for what to do when someone does do something sexist, ableist, transphobic, racist, etc. That strategy should not rely on disposability (’just kick everyone out who does a bad thing’) but on transformative justice, healing together. In many cases that means temporarily taking the person who has done a bad thing aside to talk things over with them, so that those who have been hurt can continue whatever they were doing and do not have to bear the burden of educating the person that did something wrong. 

Keeping out a demograpic group is sometimes a necessary strategy in addition to a clear anti-discrimination policy, but it is not what makes a safer space. 

Now, about safe spaces, activism and education: 

What kinds of activity we do defines how much safety we need and this is a spectrum, but every activity requires some degree of safety. 

When the purpose of an activity is healing work, processing violence we have experienced, etc. we need a very safe space. Preferably composed of people we already know and trust. This may be invitiation only.

When the purpose of an activity is in-community education, we need a space that is reasonably safe in terms of rules and that allows for some level of ignorance, flaws and imperfection in those that need to learn. (again, safer spaces are not disposability spaces that kick out anyone who does a bad thing). 

When the purpose of an activity is an open debate that included ‘our opponents’, we need to recognise that ‘open’, like ‘safe’, is not an achievable goal. A space that is open to racists is not open to anyone but the strongest people of color who can struggle through the pain of having to debate their right to exist. A space that is open to transphobes is not open to most trans people, etc. A space where anything goes isn’t safe for anyone and actively attracts people trying to normalize despicable views that should never be normalized, like nazis. We always need to be concious of where we draw the line and who we exclude when we create an ‘open’ debate.  

Finally, there are times when we need to accept that our activity is inherently unsafe, for example when the purpose of an action is to achieve through illegal action something which can not be achieved through legal action. People who are more likely to experience police brutality (people of color, trans people, etc) will be less able to participate in an action where a police confrontation and arrest is likely. Illegal activities are also by definition ‘invitation only’ because we don’t need snitches. In these cases we need to accept that this activity is inherently unsafe and inherently ‘invitation only’ we need to remain aware of that and make sure that who we value in our community does not become linked to participation in that illegal action.