Debian is the rock on which Ubuntu is built
Ubuntu builds on the Debian architecture and infrastructure and collaborates widely with Debian developers, but there are important differences. Ubuntu has a distinctive user interface, a separate developer community (though many developers participate in both projects) and a different release process.
Debian is a volunteer project that has developed and maintained a GNU/Linux operating system for well over a decade. Since its launch, the Debian project has grown to comprise more than 1,000 members with official developer status, alongside many more volunteers and contributors. Today, Debian encompasses over 50,000 packages of free, open source applications and documentation.
Ubuntu develops and maintains a cross-platform, open-source operating system based on Debian, with a focus on release quality, enterprise security updates and leadership in key platform capabilities for integration, security and usability. Ubuntu milestone releases are made every six months, Long Term Support releases are made every two years. Enterprise maintenance and support are guaranteed by Canonical for five years with optional Extended Security Maintenance available to Canonical customers. Canonical also provides commercial support for Ubuntu deployments across the desktop, the server and the cloud.
Canonical leads the Ubuntu ecosystem, partnering with public cloud and hardware providers to enable a high-quality platform that can be used free of charge, anywhere. Canonical also offers a range of services for enterprises, partners and individuals that help them manage Ubuntu.