Transition energy calculations for low-lying states of Pb and Pb²⁺ by the four-component versions of the Fock-space RCC-SD and PT2/CI methods are reported. Contributions of valence and core electron correlation are studied in all-electron calculations with the Dirac-Coulomb Hamiltonian. The accuracy of our generalized RECP and the RECP of Christiansen and co-workers is tested. The consideration of only one- and two-body amplitudes for valence electrons in the RCC method for Pb is shown not to be sufficient to reproduce valence excitations within 100-300 cm^-1. Correcting RCC-SD results by estimated contributions of triple and quadruple excitations yields an accuracy of about 200 cm^-1.