To me ventilation is intended, a draft is not. If you put a 4" hole in the side of your coop to get airflow, thats ventilation. If you put a 4" hole in your coop because you failed to make a square cut....thats a draft.
I'm no 'expert', but I'd say if it's doing bad things (chilling chickens cuz it's pointed right at them, or causing condensation on the wlls to make the coop air damper) then it is a draft; if it is only useful, it is ventilation
In the wintertime, which I'm guessing is what you are thinking about, if you put your ventilation high up on the walls, not right next to the roost, and have it adjustable os you can close down or close off parts of it when unneeded, you will be fine
All air moving through a coop provides ventilation. If it's blowing directly on the chickens, especially where they are roosting, it's a draft.
Drafts are more of a concern when the weather is cold. Having more windows open in the coop when it's 90, just helps keep the chickens from over heating. Having the same amount of air moving over them when it's freezing, will chill them.