The names "Point de Flandre" (sometimes "Guipure de Flandre") and "Rosaline" are reserved for the Belgian pieced laces described on this page. Historically the name "Point de Flandre" was sometimes used for other Belgian laces. To add to the confusion, this terminology tends to vary over time, with different vendors, authors, and translators.
Both have motifs where the 5-petal flower plays a large role. Motifs are small, and may or may not be connected with brides. In setting a standard for NNMML, "Rosaline" motifs have weavers making a twisted loop at the edge, then immediately come back into the work. In "Point de Flandre" the weavers come out, twist once or twice, exchange with the separate edge pair in a whole stitch, then the new weavers twist once or twice and go back into the work. This leaves a line of open holes along the edge of the motif. This edge stitch is also used in both laces when working a raised edgeline along the motif. If the piece has no brides the word "guipure" to the name for both types of lace.
Rosaline often, but not always has raised needlelace rings in the center of flowers, and this is occasionally found in my interpretation of Point de Flandre. Sometimes these rings are made separately, sometimes they are the coiled and buttonholed ends of passive threads. If found in Rosaline, the name gets ammended to "Rosaline Perlée".
See the NNMML Bruges Style pages for other mysterious later 19th-20th c pieced Belgian laces - ones that aren't Duchesse or other easily recognizable styles.