I have again been tempted to answer a bad question with an encyclopedia-style answer. (Questions regarding the distinction between XeTeX and XeLaTeX and how they relate to TeX and LaTeX?) Would it be better to post this as an additional answer to the linked dupe?
The network is designed to link questions that have a reference added (either in comment or in the posts), so there's no issue with adding an answer in either location. See the right-hand column when viewing the question to see which posts it may be linked to. Note that the answer has to be just that, an answer to the question.
With the broader picture in mind, it may be of more interest to add encyclopedia-style answers to the "bigger question", whichever that may be. Of course, this may be subjective as some may see the bigger question as the one with the most views/up-votes, while others may see it as the question with the most duplicate targets.
While this doesn't matter now, the mentioned question has already been closed as a duplicate.