In the context of PPM, a set of tools, strategies and techniques used to actively allocate resources within a project, program or portfolio. Resources include workforce skills, budget, inventory, technical infrastructure, production resources etc.
Whereas capacity planning is concerned with the organisation as a whole and considers resources from a high-level point of view, resource management handles resources more actively and with more granularity within a smaller perimeter (a project, a program or a portfolio).
Related articles: planisware enterprise demo: capacity planning, planisware enterprise demo: operational resource management