Once you’ve got your eye in, scotch and bourbon are quite different. Many (although not all) scotch whiskies have peat in their flavour profile (a kind of smoky, salty, earthy flavour which is very distinctive), while bourbons never do. Bourbon is almost always quite a lot sweeter than scotch.
They’re also made quite differently. Bourbon is mostly corn, and often has lots of rye and wheat in the mix, whereas scotch is mostly made of barley. Bourbon is always aged in new oak barrels, whereas scotch is mostly aged in second-fill barrels (which might previously have been used for bourbon, wine, sherry, port, cider etc.).