CCC 1184 The chair of the bishop (cathedra) or that of the priest “should express his office of presiding over the assembly and of directing prayer.”1
The lectern (ambo): “The dignity of the Word of God requires the church to have a suitable place for announcing his message so that the attention of the people may be easily directed to that place during the liturgy of the Word.”2
1 GIRM 271.
2 GIRM 272.