Fine-tuning is the act of re-training a pretrained model on a new dataset/task, it has nothing to do with freezing part of the network or not (at lest in the wat we use it in the course, which is the general way it is used in the published literature AFAIK). Freezing part of the network might help in some situations (like computer vision) but it doesn’t really help for Transformer models, usually it gives worse results.