TeX là ngôn ngữ lập trình cho việc sắp chữ. LaTeX là các macro để việc định dạng được thân thiện hơn

In TeX, you learn the basic things and use that to do what you want.

In LaTeX, you look for a specific package that already does what you want and use it.

The implications are:

In TeX, you need to learn all the basic before being able to do most tasks. Thus the initial learning curve is steep.
- But you also learn how to program, thus you have the power of the computer (e.g. doing repetitive task)
  
  LaTeX has e.g. python package, but it only has loose integration with the TeX layer (e.g. it’s not very easy to measure the width of a box, if you e.g. want to automatically determine column width).
However, once you’ve learnt all the basics, you can do everything1, instead of looking up a new package you define your own command to do what you want.
- For a comparison, TeX is a full programming language (imagine Python), and LaTeX is like a DSL (domain-specific language) (imagine the game engines that allow you to make games without coding).
  
  Wikipedia link for DSL. (for whatever reason, at the moment the Wikipedia page lists LaTeX as external domain-specific language, while it’s obviously embedded in TeX…)