Open data catalogues provide curated, machine-readable (e.g. xml) shareable (free, public domain or creative commons licensed) listed, data sets. Curators are responsible for data integrity and version control. Datasets can be used by anyone to create apps, map, visualizations, etc.
What is open government?
Open government is a philosophy that advocates transparency, public participation, and collaboration in governance. Advocates for open source government seek widespread use of open source ICT's (information and communication technologies) and the addition of open source content (documents and data) to government websites and government publications services.