I'd just comment this way.
There are a lot of terms interchanged for alluding to non-monogamous or open relationships.
There's been endless debates about what a definition of 'polyamory' really is and probably there always will be. You can find a few on here to help you better understand the quandary.
The problem basically comes down to a lack of a definition of love - the 'amory' part.
So I find it helpful to understand and explain to others that if you want to make some distinction - or quasi-definition of polyamory, you key in on the concept that you are in multiple relationships and that there's more depth, a deeper connection to those relationships.
This only contrasts with what are often early 'dating' type relationships or the many forms of sexual openness where there is limited desire or time for any deeper connection and the focus may be simply more of a sexual nature. There's a sliding scale it seems on when that 'depth' slides over to the 'love' phase.
Hope that helps.