Hi Shamus Sim
It is showing version 1 of Whisper is Whisper Large v2 model.
So, there is a model architecture difference for version 1 as mentioned in hugging face model card details
Reference is model card details from Azure OpenAI foundry
Azure product team also does additional finetuning before hosting the models in Datacenter which might be reason behind the better results.
https://github.com/openai/whisper/blob/main/model-card.md
Hope that helps.
Thank you.