I'm assuming the OP is referring to Black Patent when he says Black Barley and based on that yes, there's a HUGE difference. Black Patent is very harsh, very bitter and in my opinion should be used very sparingly. Roasted Barley on the other hand has a yummy roasted grain flavor.
I just made a bulk purchase of several grains these two included and as I was moving them to their respective storage containers I munched on a few grains of each one. Next time you’re at your LHBS try a couple grains of each and believe me, you’ll see the difference. Roasted Barley tastes good and Black Patent will send you running for something to wash it down. I’m not saying you shouldn’t use Black Patent, it goes in all my stouts, it’s just extremely harsh.