No change of government between orders: it's the one government which ordered the proposed Barracuda-based 'Attack' class in 2016, changed its mind, cancelled the order and has now changed from conventional propulsion.
The only political change is the Prime Minister - the one from 2016 was challenged from within the governing party and was replaced. The present governing party has been in government since 2013.
Also, perhaps in future we'll look at fine-print related to the basing of strategic items in Australia as the key element of this deal. The submarines might just be the headline rather than the substance of this story.