If you were to say bourbon is whiskey, that wouldn't be incorrect. Bourbon is a type of whiskey, meaning all bourbon is whiskey but not all whiskey is bourbon. What makes bourbon different from other whiskeys is the way that it is made. For a whiskey to be classified as bourbon, it needs to be distilled from a mixture of grains that is at least 51% corn. The corn is what gives the bourbon its sweet flavor.
Another reason why whiskey and bourbon are different is bourbon has to be aged in a new charred oak barrel for a minimum of two years and cannot have any additives or coloring. Other whiskeys can be aged in barrels that have been previously used. They also do not have to be whiskey barrels.
Bourbon has to hit certain ABV marks. Before the bourbon is bottled, is it filtered and diluted down to no less than 80 proof. Other whiskeys have different ABV standards for distilling a barreling.
Lastly, you could of heard that in order to be bourbon it has to be made in Kentucky. This is not true. Bourbon is allowed to made outside of Kentucky but for it be designated "Kentucky Bourbon" it has to be made in Kentucky. The next time you order a bourbon, just remember you're getting a glass of not just whiskey, but a specific kind of whiskey.