The standard installer likes to make decisions for you. It installs shortcuts, updates telemetry settings, and often defaults to the "Current Branch" update cycle. The offline installer, particularly when paired with the Office Deployment Tool (ODT) , gives you god-mode control. You can dictate exactly which apps you want (say, skipping Publisher and Access) and which ones to ignore. You can install Office 365 without linking it to the cloud on first boot, creating a cleaner, leaner system.
(Default, recommended for most):