I suppose you are referring to Knowledge Distillation/Model compression.
A model’s output(called teacher model in this context) is what generally referred to as soft label. It is called soft because the output may not be strictly something like [1, 0, 0] for a 3-class classification task, instead it might something like [0.85, 0.1, 0.05].
This soft label is used to train a much smaller network(called student model) instead of using the hard targets.
Hope this makes sense. Thanks.