One difference (besides the birds) between the Vespasian restoration and the Republican original discussed the other day is certainly the posture of the goddess Roma herself. On the imperial aurei she sits erect with a shorter scepter. On the republican denarii she leans forward and the spear extends far over her shoulder. She lets it take her weight. Her arm which holds it rests on her thigh. Her gaze is seems full occupied by scene before her. She is at rest, almost a mournful pose, certainly a contemplative one. In that, it strongly reminds me of the above Greek relief from Athens in the Acropolis Museum.
The gem, an imprint of which can be seen here: http://arachne.uni-koeln.de/item/marbilder/2688807, does not have the same contemplative pose. Like on the aurei she sits upright holding her scepter instead of letting it hold her. The birds are intermittent. [A. Furtwängler, Beschreibung der geschnittenen Steine im Antiquarium, Königliche Museen Berlin (1896) Cat. no. 9561.]
There is also this gem [http://arachne.uni-koeln.de/item/marbilder/2688808] with Roma and wolf and twins plus tree and Victory, over all a very different composition.