The main difference is liquidity to do the developments. By funding the debt, bankers can repackage that to instituations or pay out an interest rate to saving account holders.

Other than that, the 600 million goes into materials, labour, localised workforce, job creation etc. etc. and when the housing is completed the apartments offer cheaper rents, more accommodation etc. etc.

Society improves off that debt issuance.

It's why Strike is offering loans against bitcoin, something like 100k for 2.5BTC. This is a debt facility that allows you to do things (hopefully that make you a return) and pay off the debt.