How we do use an event license vs a standard license?

Could you clarify what an event or standard license would be? Maybe login/user licenses?

I am novice with the Appian product so I may be wording my question incorrectly. It is our understanding that we have a certain number of user licenses and we have certain number of 'event' licenses. We don't know the difference between the license types and can't find anything in the documentation about an event license. What we are wanting to do is launch a survey for our locations to fill out. We have say 100 user licenses and 1000 event licenses. We need the survey to go out to 500 locations. What we are trying to do is understand how we can launch the survey to the 500 locations and comply with our licenses. The numbers I used are made up for the sake of the argument but you get the picture.
Thanks.