I've been trying to find a way to explain the difference between identification and mature object relating to non-psychological audiences. How about the boxing metaphor?
Imagine that a healthy relationship is one in which we are able to spar with our opponent. We risk receiving punches, yet we are able to give them too. We stay in the ring, in the contest. There is the right kind of distance between us, so that we can get each other in our sights, dance around one another, and take part in the fight. (The metaphor only works if you get past the idea that hitting someone is bad...! It's a metaphor, right!)
Imagine now that the fight seems too threatening - our fear of what the other will do to us - or what we might do to them - is overwhelming. There are two options. One is that we cower on the other side of the ring. We withdraw, step away, perhaps even climb out of the ring altogether. This is akin to psychological withdrawal, shutting down, avoiding contact with others, avoiding any close relationships.
The other is that we move right up to them, we become so close to them that they have no room to hit us. Caught up next to them, needing to move around with them in case any distance opens up, making their movements our own, mirroring or inhabiting the equal but opposite flip-side to any real movement so as to keep a subtle stasis in play, avoiding being hit but also avoiding hitting, any possibility of a real object relationship is avoided. This is identification.
Identification can involve becoming so close to another, over-familiar, intrusive, under-the-skin, that real relating, real boxing, is completely avoided. In this close proximity, there is no room in which punches may be traded.
Needless to say, giving up identificatory forms of relationship can be scary. The possibility that we may be hit and not be able to hit back, or that we may hit and hurt our boxing partner who we also care about, may seem too much. But, at the end of it, we can move around again, freely, dance around the ring with our partner, trading the punches of love and hate.