Is there a difference between the online service and the self-hosted application?

Kanban Tool On-Site is the on-premise version of the Kanban Tool service, which you can run and manage in your own, secure environment.
It provides the same unprecedented promise and experience as the online kanbantool.com service while remaining fully under your control.

The most important difference is that the online service data is stored on our servers.
The On-Site version is installed on your company server, and requires no access to the Internet, so you do not need to worry about sending sensitive data to the cloud. You install it as a virtual machine on your server and manage updates and backups according to your company policy.

What that also means, is that Kanban Tool On-Site lacks Internet-based features, e.g. Zapier or file hosting services integration i.e. Google Drive, Dropbox, Box, and OneDrive. Kanban Tool On-Site is preset to be able to run in a completely web-isolated environment, keeping your data as secure as possible.