Difference between Crystal and Caramel

I brewed up a batch of the BYO recipe Fat Tire clone recently. The clerk told me to use caramel rather and crystal malts. The beer came out very dark and higher gravity that expected. Is this because of the different malts or are they interchangable? We also used LD Carlson Pilsner DME rather than the Laaglander. Below is the recipe for reference:

•5 lbs. Laaglander plain extra-light DME
• 0.50 lb. crystal malt (20° Lovibond)
•0.50 lb. crystal malt (40° Lovibond)
• 0.50 lb. carapils malt
• 0.50 lb. Munich malt
• 0.50 lb. biscuit malt
• 0.50 lb. chocolate malt
• 3 AAUs Willamette pellet hops (0.66 oz. at 4.5% alpha acid)
• 1.33 AAUs Fuggle pellet hops (0.33 oz. at 4% alpha acid)
• 2 AAUs Fuggle pellet hops (0.50 oz. at 4% alpha acid)
• 1 tsp. Irish moss
• 2/3 to 3/4 cup corn sugar to prime Wyeast 1056 or BrewTek CL-10

caramel and crystal malts are the same thing.

Your beer came out too dark because of the 1/2 pound of chocolate malt. In a five gallon batch to get the color you are looking for, I would have simply added 2-3 oz of chocolate or subbed C80 for the C40.

8 oz of choco made you a brown ale.

This came up before. There is a difference between crystal and caramel malts but I don't remember exactly what it was now. There is a thread or more floating around about it. Caramel malts are 'newer' and supposedly a tad less harsh if I remember correctly. Problem is, you don't know what you are getting most of the time. I traced one brand that changed from caramel to crystal by the time it hit the LHBS.

from BYO

Crystal malt: This is the British term for saccharified and drum-roasted malt. It can be roasted to different degrees to provide a range of colors. The most common range used in the UK is 70° to 80° Lovibond, which tends to produce deep red colors and a strong caramel flavor. These malts may be marketed as light, medium and dark crystal. They are used in pale, amber and dark ales and lagers, and leave a beer tasting sweeter.

Caramel malt: The American term for crystal malt. American producers tend to market these malts by their Lovibond rating. The most common colors used in the U.S. are 30° to 40° Lovibond, but this statistic is skewed because it includes all the caramel malt used by the big commercial producers, who use it in paler, milder-tasting beers. It’s typically used in pale, amber and dark ales and lagers.