Rigorously grown in various places including California and Australia, the Yen Ben lemon has a smooth rind to it and a high juice content. If we're going just by the look of the fruit, then not much seems different. Both the Lisbon lemon and Yen Ben lemon are oblong with short tapered ends with a vibrant yellow color to them that is simply unmistakable. Where things get different is the Yen Ben lemon tree. Perhaps because the trees are precocious, according to Citrus Variety, they look more bush-like when laden down with lemons. The leaves also appear darker in color and a bit thicker than the typical lemon tree.