Front views of Ciro Ballerina and Trifari Ballerina

On these images you can see there are small differences that show the maker of the mould for the Trifari piece has more ‘artistic flair’ than the one who created the Ciro mould.
The centre line of the bodice on the Ciro one (left) is absolutely straight while the one on the right has a slight curve to it.
The stones in the Ciro bodice are placed in rows which gives a more rigid feel to the piece than the random placement seen on the right.
The front foot on the Ciro has the toes bending too far back into a position which would not take the dancers weight whereas the Trifari one is gracefully in line.

The back foot of the Trifari piece is malformed (thin in the ankle and flat on the instep) but my experience tells me this is likely to be a casting fault where insufficient metal travelled into that part of the mould rather than a modelling error.

The skirt of the Ciro piece has been attached so it stands well proud of the legs which makes the brooch less stable when worn.

I think that the stones used in the Ciro piece have less facets than those used in the Trifari piece but it is very difficult to be certain.