Russia is the largest country in the world. To help run its vast lands it requires a complicated set of Federal Subjects that include Oblasts, Krais, Republics, Federal Cities, Autonomous Okrugs, and an Autonomous Oblast.
These Federal Subjects of Russia are not all the same, and since Russia is an asymmetric federation, some of the subjects have more powers than others.
The federal subjects of Russia explained:
Oblasts, Krais, and Federal Cities are average Federal subjects, having the right to their own legislatures, while Republics,
Autonomous Okrugs, and the Autonomous Oblast are meant to provide additional rights to Russia’s minorities.
Republics get their own constitutions and official language status, while the Autonomous Okrugs and Oblast get some language rights. Additionally Autonomous Okrugs can, but not always, be divisions of other federal subjects.
The difference between Oblasts and Krais is just a historic one where Krais were once the frontiers of Russia. The federal cities are like oblasts but they only have 1 city in them.
The jewish autonomous oblast is perhaps the weirdest federal subject of Russia, since less than 1% of its population is jewish and its existence is a leftover from the soviet era.
Kaliningrad Oblast is an exclave of Russia, completely detached from the rest. You can learn why Russia and other countries have exclaves in this video:https://youtu.be/elybAzSVSHc
You can learn why Crimea and Istanbul are so important to Russia in this video:https://youtu.be/uxWdmi4vsaU
Instrumental Russian National Anthem
From Russia With Love - Huma-Huma