Besides some shared basic characteristics, Arabica and Robusta couldn't be more different. Arabica plants are fussy. They are happiest grown at relatively high altitude (usually somewhere between 600m above sea level – 2200m above sea level); not too much rain, not too little; not too hot, but not too cold either; nice, bright sunshine, but also a fair amount of shade. Arabica plants are more susceptible to pests and disease, so they require a bit more attention and care, but they don't want to be handled too much either. (Needy much?) But! When all of the conditions are just right, Arabica plants produce a glorious variety of flavor profiles, not unlike wine, as you may know. The higher sugar and lipid content plays an integral part in balancing the coffee's natural nuances. Its caramelization during the roasting process is what does the trick. This is why roasting is an artform. The roaster has to know just how far to push the coffee or when to hold back to best accentuate the natural properties of that particular variety to be roasted. -- But, I digress.
Robusta plants, as the name kind of implies, are much more robust than their Arabica cousins. They aren't too picky about altitude, feeling right at home at about sea level up to 800m above sea level. They enjoy the wetter, hotter conditions of the tropics. They are much more resistant to disease and pests, and they aren't particularly sensitive to handling. There isn't nearly the variety in flavor profiles, but here's the kicker, Robusta beans are said to have TWICE the amount of caffeine. On paper, Robusta plants seem to be the wiser choice for coffee growers, so why in the world would farmers gravitate to Arabica when it's so much more finicky and less caffeine to boot? Well, it’s the taste. Many western coffee drinkers liken the taste of Robusta to burnt plastic or rubber. This is why you'll hardly ever find 100% Robusta in the U.S. You will, however, occasionally come across a blend of Arabica and Robusta, usually touting its dangerously high caffeine levels.
Unfortunately, ACR doesn't sell Robusta coffee, so we won't be able to offer you a taste test. However, if you do happen across some, definitely give it a shot (bah-dum-bum-tssss). It is absolutely worth it, if for no other reason than to educate your palate. In recent years, the coffee drinking community has become more and more educated on the different variables that make up the taste of their coffee, be it the altitude at which it was grown, the region, the varietal, the roast level. The points mentioned here are really just the basic differences between Arabica and Robusta. Hopefully, introducing you to Arabica's wild-eyed cousin will serve to broaden your scope of coffee a little.