Manga is mostly visual, with lots of illustrations and panels to tell the story. Light novels, on the other hand, have more text and focus more on descriptive writing.
The big distinction lies in how they convey the story. Manga relies heavily on pictures and visual cues. Light novels, though, are driven by words and detailed descriptions. Another difference is that manga is often aimed at a wider audience, while light novels might target a more specific demographic, like young adults who enjoy immersive reading.