What is the difference between Bulgarians and Bulgars?

They were both Turkic peoples of Eastern Europe, but the Bulgars settled on the Volga, where Tatarstan and Chuvashia are now, they founded the northernmost Muslim state on the planet – Volga Bulgaria, it was conquered by the Mongol-Tatars in the 1230s and 200 years later there the Kazan Khanate appeared.
The Turkic people were called Bulgarians, who left the lower Don to the west and settled about 681 on the southern bank of the Danube. It was led by Khan Asparuh, and soon they mixed with the Slavs and adopted Christianity.