the idea that one could determine how much one grieves a loss from tears is absurd. there is no way to know how much someone is hurting without in depth counseling and brain scans.
Yes, they could have experienced the same loss. Different people experience different things in different ways. Even though the teen may not have cried, there are still other processes that the teen goes through mentally and emotionally that signify that they went through grief. Crying, though is a common sign of loss, is not the <em>only</em> sign of loss and/or grief. And you also can not measure the amount of grief anyone has just by looking at them.
Hope that makes sense, and helps! Have a good day and remember to be tiger fierce!! :)