The difference is that the Allen Institute models have open training data, not just open code and weights. Meta doesn't share the training data you would need to reproduce their final models. For many uses open-weight models are nearly as good, but for advancing research it's much better to have everything in the open.

Reading their paper, it wasn't trained from scratch, it's a fine tune of a Qwen3-32B model. I think this approach is correct, but it does mean that only a subset of the training data is really open.