What is actually different?
Xero is an accounting product. It is very good at being one, and a large ecosystem has grown around it — a marketplace of apps to add the things it deliberately does not do, and a profession that has standardised on it.
Bizzle is not trying to be a better ledger. The ledger is table stakes. What it adds is the work around the ledger that small businesses actually lose evenings to: the phone that rings while you are on a job, the invoice nobody chased, the receipt that never got filed, the quote sent three days late.
The practical difference is what you end up buying. A Xero setup that answers calls and chases debtors is Xero plus a receipt tool plus an answering service plus a chasing app, each with its own subscription and its own login. Bizzle is one system and one price, which is either a simplification or a constraint depending on how attached you are to picking your own tools.