It means for 4.7 they trained a new base model with different architecture, different pre-training data (later knowledge cutoff), and a new tokenizer. Vs finetuning an existing model, which was the case for 4.6, and probably for 4.8.

do you mean pre training? so 4.8 is just post training of an old pretrained model?

btw where do they tell you how they trained the model.