Hi sweetheart so on ao3, people tend to inverse the two terms... so since my account is mainly for ao3 recs i decided to match the most common ao3 use.
Switch = they change sex positions (penetrative), vers = they change headspace (as you call it uhuh)
In real life, lgbtq+ people use the terms like so
vers = they change sex positions (penetrative) switch = they enjoy both headspaces (dom/sub)