Augment means to make something greater, larger, or stronger. It focuses on increase. If a company augments its staff, it adds people so the team becomes bigger. If funding augments a project, the project has more resources than before.
Supplement means to add something extra that supports, completes, or improves what already exists. It does not usually suggest full replacement. A teacher might supplement a textbook with videos, or someone might supplement a healthy diet with vitamins.
The simplest contrast is this: augment is about growth, while supplement is about adding support.
- The new software will augment the team’s productivity.
- She used case studies to supplement the lecture.
- Vitamins may supplement a diet, but they do not replace balanced meals.
If you mean make larger or stronger, choose augment. If you mean add something extra to help or complete, choose supplement.