[AccessD] Confused by One to Many versus One to One

I almost never make relationships one to one, and yet my databases always
seem to "work." By work, I mean that I never seem to run into situations
where I cannot accomplish what I want to, in terms of record insertion,
queries, etc. So I now have a situation where maybe that is not a good idea.

 

I have Order and Product tables, one order can contain many products. So I
required an OrderProducts table to distribute the same OrderID across
numerous ProductIDs.

 

My question is, should the relationship between the Order and OrderProduct,
on the OrderID and FKOrderID, be 1-to-1, or 1-to-many?

 

Likewise, the same question for the OrderProduct and the Product, on the
ProductID and the FKProductID?