Is it true that all bourbon is whiskey but not all whiskey is bourbon?

Yes, it is true that all Bourbon is a type of whiskey, but not all whiskey is bourbon. Bourbon is a specific type of American whiskey that must meet certain legal requirements, such as being made from at least 51 corn and aged in new charred oak barrels. Other types of whiskey, such as Scotch or Irish whiskey, have different production methods and regulations.