The H-R diagram and the color-magnitude diagram (CMD) are similar but serve slightly different purposes. The H-R diagram plots temperature (increasing from right to left) against luminosity and is more theoretical, showing intrinsic stellar properties and evolution clearly. The CMD, on the other hand, uses color as a proxy for temperature and absolute magnitude instead of luminosity, making it more of an observational tool but also more prone to scatter from interstellar dust. While the overall structure of both diagrams is similar, the H-R diagram is cleaner and shows a more precise trend, whereas the CMD shows the raw photometric data and thus will appear more scattered.
