Well, governments fund roads, schools, etc, and they don't expect to make financial returns on those.
However, the national broadband network is funded through government loans, but expects to make a profit on the returns from it.
So there is quite a difference in terms of the Government budget. The former are a cost to the budget, with ongoing expense and no expectation of any monetary returns. The latter is forecast to take nothing out of the government budget.
The government is LOANING the money and are expecting to make a profit out of the effort.