Abstract: Ultradiffuse galaxies appear largely smooth in survey imaging, yet they host diverse compact stellar systems. In this talk, I will present our spectroscopic study of compact stellar populations and internal kinematics in 44 low-surface-brightness galaxies spanning the red sequence, green valley, and blue cloud. Their compact stellar populations vary systematically with host-galaxy color: blue systems commonly host nebular emission-line clusters, while clusters without detectable nebular emission are also, on average, brighter than those in red-sequence galaxies. The emission-line clusters can also serve as kinematic tracers, revealing internal motions that are difficult to measure directly from the diffuse galaxy light. The resulting dynamical masses generally exceed stellar masses, with the inferred dark matter contribution varying by about an order of magnitude.