A gravel jersey is worth considering if gravel or adventure riding is your main thing. While a road jersey will work in a pinch, it's missing key features that matter on rougher terrain. Gravel jerseys use more durable fabrics that resist snags from branches and hold up better to the occasional tumble—road jerseys are too delicate for that.
The biggest difference is storage. Gravel jerseys typically add extra pockets or larger pocket openings so you can carry more snacks, tools, and layers for long days on remote roads where convenience stores are scarce. The fit is also a bit more relaxed than a road jersey, which is nicer when you're sitting more upright on a gravel bike.
Think of a gravel jersey as the versatile middle ground: durable enough for light off-road use, still sleek enough to not feel baggy, and built to carry everything you need for all-day adventure rides.