Making something visible refers to using techniques like microscopes, telescopes, staining, and chromatography to render objects observable that otherwise cannot be seen. Visualizing something relies not just on techniques but imagination, using tools like charts, diagrams, and maps to understand concepts and processes. The document advises avoiding saying an experiment "visualized" differences when the technique only made them "visible", and to say staining "made visible" rather than "visualized" since staining only reveals objects, not conceptualizes them.