1. Where it runs. QuickBooks Online lives entirely in a browser or its mobile app; nothing installs on your computer. QuickBooks Desktop is software you install locally, with a company file (a .QBW file) that lives on that machine or on a server you set up yourself.
2. How you pay for it. Online is always a subscription, billed monthly or annually per company. Desktop used to be a one-time purchase, but Intuit has shifted its main editions, Pro Plus, Premier Plus, and Mac Plus, to annual subscriptions too; QuickBooks Desktop Enterprise is sold on its own separate cycle. Online's subscription bundles software updates automatically; Desktop needs its own maintenance releases installed.
3. Multi-user access and collaboration. Online includes simultaneous multi-user access right in the plan tier (Simple Start allows one user, Essentials three, Plus five, Advanced twenty-five), reachable from anywhere. Desktop's multi-user mode needs QuickBooks Database Server Manager set up on a shared network, and using it outside the office means adding separate remote-access or hosting software on top.
4. Feature parity gaps. Desktop still has things Online has never fully matched: a native Sales Orders document for tracking backordered items between an estimate and an invoice, industry-specific editions (Contractor, Manufacturing and Wholesale, Nonprofit, Retail), and deeper inventory costing like FIFO in Enterprise. Online's strength runs the other direction: a much bigger connected-app marketplace, automatic bank feed matching, and full functionality from any device without installing anything.
5. What actually decides it. If your business leans on a Desktop-only feature, a Sales Order workflow or an industry edition's built-in reports, that usually settles it on its own. If what matters more is working from anywhere and connecting other tools, Online tends to win, even with the feature gaps.