* Basic: This implies the most fundamental knowledge or skills needed to understand or perform a task. It's the very minimum required to get started. Think of it as the absolute foundation.
* Elementary: While also representing a foundational level, it suggests a slightly more structured and comprehensive introduction to a subject. It goes beyond just the bare minimum and incorporates a broader range of concepts and skills, albeit still at an introductory level. It implies a more systematic approach to learning.
Analogy:
Imagine learning to play the piano.
* Basic: Knowing how to sit correctly at the piano, identify the notes on the keyboard, and play a few simple chords.
* Elementary: Learning basic music theory (notes, scales, rhythm), simple melodies, and practicing finger exercises, along with those basic elements.
In short, "basic" is the absolute bottom rung, while "elementary" is a step or two higher, encompassing a more developed and structured introduction to the subject. The difference isn't always stark, and the context greatly influences their meaning.