preferable(better than some other option) adjective [UK: ˈpre.frəb.l̩] [US: ˈpre.fə.rəb.l̩]Walking is preferable to sitting. = Es preferible caminar a estar sentado.
preferiblemente adverb
preferably(in preference) adverb [UK: ˈpre.frə.bli] [US: ˈpre.fə.rə.bli]We want an assistant, preferably someone with experience. = Buscamos un asistente, preferiblemente alguien con experiencia.