LaTeX is an advanced method of making documents. Documents written in LaTeX are written in plain text with set elements, which it is then compiled into a PDF.
LaTeX is similar to Markdown in that it serves as a language rendering plain text as a stylized and formatted document.
Markdown directly can be understood and rendered, whereas LaTeX serves as instructions to a compiling tool to compile it into a PDF document. It is also far more advanced and complex, such is the reason for this guide.