Markdown compiles to a subset of HTML, whereas LaTeX is able to express pretty much anything that can possibly be put in pages of PDF.
As such, Markdown is very clean and focused. You can figure out all features of Markdown in a few minutes. As you know, LaTeX can be excruciatingly complex but astonishingly powerful
Markdown focuses on getting anything that isn't content out of the way. LaTeX defines it, rather explicitly.
I use both. I used to use LaTeX for everything, but I realized I didn't really need the power. Now I use Markdown, and have a custom style sheet for the html it creates (for printing, using the awesome Marked.app).
If you use pandoc to convert your markdown to tex, it will pass through any TeX commands embedded in the document, so you can get the best of both worlds.
As such, Markdown is very clean and focused. You can figure out all features of Markdown in a few minutes. As you know, LaTeX can be excruciatingly complex but astonishingly powerful