Eureka lemons are pretty interchangeable with Lisbon lemons, so they may be easily available at your local grocery store or farmers' market. When it comes to telling the two apart, Eureka lemons have a thicker skin that makes them better for providing zest in recipes. Monrovia writes that Eureka lemons also produce fruit year-round (which we love because the more lemons, the merrier). The flower color is white and the oblong leaves a deep green hue. But what sets Eureka lemons apart is the bronze-purple new growth they feature.