A Debian Developer is someone who has certain priveleges within Debian.
They have been through the NewMaintainerProcess, and now are required to uphold the Social Contract, and are trusted to maintain the integrity of Debian.
They have three main abilities for their position
- Ability to upload. Their GPG key is in the Debian keyring, meaning that uploads signed by them will be accepted in to the archive.
- Ability to vote. Occaisionally there are votes (known as GeneralResolutions or GRs), in which Debian Developers get a say in how the project is run.
- Access to Debian infrastructure. One a Debian Developer is accepted they are given access to parts of the Debian infrastructure others are not allowed ot access. This includes things like porting boxes, which allow them to diagnose problems on an Architecture they do not own.
It is possible for a non-DD to contribute to the distribution without these things. In fact it is only the voting that is purely for Developers, (sponsored uploads get around point 1, and certain boxes are available to other on request, getting around point 3 somewhat).