Conformations of neutral and charged brushes on spheres have been explored for diblock and triblock copolymers adsorbed on colloidal particles and associated in micelles. The variation of layer thickness L with adsorbed amount for a wide range of core radii R (0.04 < L/R < 20) agrees well with the blob model of Daoud and Cotton for neutral polymers and a new "electrostatic blob model" for semirigid polyelectrolytes. The latter combines the Daoud and Cotton model with the electrostatic wormlike chain theory for polyelectrolytes to account for chain stiffening and excluded volume interactions inside the blobs.