The Federation is an interstellar federal republic, formed by planetary governments that agreed to exist semi-autonomously under one central government based on the principles of universal liberty, rights, and equality. The members share their knowledge and resources.
As one of the most powerful interstellar states in known space, the Federation encompasses 8,000 light years and covers at least 1,000 planets. It has more than 150 formal member worlds.
The Dominion was a major interstellar state in the Gamma Quadrant. Technologically advanced and millennium old, the Dominion was founded under the absolute rule of a group of Changelings known as the Founders, whose will was carried out by the Vorta and the Jem'Hadar. The Dominion was dedicated to imposing the Founders' vision of "order" upon the universe, i.e. bringing all other civilizations under its control.