What is actually different?
QuickBooks is one of the two products most UK accountants will name unprompted. It is broad, it is well supported, and its self-employed tier is genuinely good at the specific job of getting a sole trader to a tax return.
Bizzle overlaps with the accounting part and then keeps going. The phone gets answered, the quote gets sent from the van, the invoice chases itself, and the receipt is filed against the transaction before you have got home.
So the comparison is not really feature-by-feature. It is whether your bottleneck is the books, in which case QuickBooks is a sound answer, or everything around the books, in which case more accounting software will not fix it.