Compare the register and purpose of textbook-style informational writing with feature-article writing on the same topic.
The same true information can be written in very different voices depending on its purpose. A textbook paragraph aims to be efficient and neutral -- a quick, reliable reference. A feature article aims to engage a reader's attention and imagination, often through pacing, sensory detail, and a more narrative structure. Neither voice is more "true" than the other; they simply serve different reading purposes.
Compare two versions of the same fact about medieval castles. Textbook version: "Medieval castles used moats, thick walls, and narrow windows called arrow loops for defense against attackers." Feature-article version: "Approach a medieval castle as an attacker, and the building itself seems to fight back before a single soldier appears -- a moat swallows your ladders, walls thicker than a room refuse to crack, and slit-thin windows let defenders fire arrows at you while staying almost impossible to hit in return." Same facts. Completely different reading experience.
Mastery looks like: They can identify the shared facts underneath two differently voiced passages and rewrite a flat sentence in a more narrative, feature-article register without changing its facts.
Common stumbles: Assuming the more dramatic or engaging version must be less accurate, or the plainer version must be more trustworthy, simply because of tone.