I can only use myself as an example.
I can explain this from two perspectives. My old friends and "now"
1st My friends back home, if they saw my life as is, would assume I am dating...well currently 7 women. I go on "dates", out for drinks, dinner, beer, coffees etc. However the reality is I have a lot of female friends.
When I "date" someone I am specific. I ask them out on a date. I try not to leave anything veiled or possibly hidden. This saves me from getting hurt if I expect something to be a date, and it wasn't, which has been
With my friends, there is always a chance it could evolve into more since I leave that door open. But it doesn't necessarily overlap. I have one friend I have been known to cuddle and snuggle with at the bar. But there is 0 potential of anything beyond friendship. We are just that close.
As long as you openly discuss it, it will work. The nice thing about poly is I find communication easier, not harder. Being single there is a lot of guess work. So far, in my encounters, the "just ask" approach works, as long as people realize they may not always get the answer they want