What is the difference between blues and rhythm blues?

Blues is a genre characterized by its expressive melodies, often featuring themes of sorrow and heartache, typically built around a 12-bar structure. Rhythm and blues (R&B), which evolved from traditional blues in the 1940s, incorporates a stronger emphasis on rhythm, upbeat tempos, and elements of jazz, gospel, and soul. While blues often focuses on emotional storytelling, rhythm and blues tends to prioritize danceability and a more polished sound, appealing to a broader audience.