The difference between nested posts in Jekyll

Today I learnt that the only difference between a post saved under _posts/ and another in _posts/til/ is the path. This has enabled be to use the following logic in Liquid for the blog:

for post in site.posts
  if post.path contains 'til'
    <!-- Render TIL post title and date -->
  endif
endfor

A post saved under _post/til/ would have a post.path of _post/til/2019-01-01-post-name.md.

On another note, I also learnt that you can’t add valid Liquid code to a post because it renders. That’s why the above snippet doesn’t have the parenthesis - percentage Liquid syntax.