Remember the first "truth" about caffeine in beans? Well that was a bit of a stretch. The whole truth is that each type of bean has the same amount of caffeine. The two main types of coffee beans are Robusta and Arabica.
Robusta beans are more disease and pest-resistant, typically produce a larger yield and can be 40-50% cheaper. They also have a stronger, harsher taste when roasted, think burnt wood, grain-like and bitter.
So why roast or drink Robusta? Well, some Robusta can actually be tasty, if roasted and blended appropriately (Robusta beans are usually used in blends). Think of Robusta beans as the oatmeal you add to a meatloaf. It makes the meatloaf go further, and can actually impart flavour into the loaf if used well.
Most importantly: Robusta beans have twice the caffeine compared to Arabica beans.
And some days this is important. Really, really important.