Czar was the title used by the monarchs of the Bulgarian Empire since 913 and the Russian Empire between 1546 and 1917.
Tsarism was a political system that reigned in Russia from 1547 until the revolution of 1917. Tsar was the title given to the Russian Emperor. The Tsars of the Romanov dynasty, which were in power from 1613 to 1917, ruled absolutely, in which the tsar was confused with the state.