What are the differences between XeLaTeX and pdfLaTeX?
latex, pdflatex, xetex
Solution
PdfTeX and XeTeX and the equivalent commands for `latex` are two implementations for the same purpose, as you have pointed out already. The Wikipedia articles have more details on the history and development.
One of the main differences from an operational point of view is that XeTeX has better support for fonts -- in particular you can use system fonts instead of only TeX fonts. It also has better support for non-latin character encodings.
Problem
There are multiple TeX typesetting engines. Both commands (`pdflatex` and `xelatex`) generate a PDF. What is the technical/effective/historical/etc. difference between these two commands? I'm using TeX Live.