Translation:Because Korglach defeated Lurveng, Lurveng's house is sad.
Difficult to say, really. I suppose context could make it clear if there is a difference. For instance, I would say that jey could only be used when the contest is between the subject and object, but lujmoH could be used to describe third-party interference in a contest causing the object to loose the contest. So using lujmoH in a sentence like the one given by Duolingo might sometimes have a slight implication that Korglach may not have been directly involved in the contest, but rather interfered in the contest. jIHmo' ghaH jeylu' and ghaH vIlujmoH are significantly similar, but the different grammar needed makes it clear that they are not synonymous.