In this paper, I review most of the current knowledge about magnetic field topologies and surface differential rotation of cool active stars like the Sun. I concentrate in particular on the most recent observational results, derived from studies on dynamo field generation in stellar convective envelopes from magnetic imaging of very active rapidly rotating low mass stars, and present the elements of evidence that dynamo processes in these active stars are distributed throughout the whole convective zone, rather than being confined in a thin interface layer as in the Sun. I finally discuss the new discovery that dynamo magnetic fields generate feedback effects on the global dynamics of stellar convective envelopes.