I would say blue acara just because of the lack of colour and spangles compared to juvi gt's at my lfs. Although they do have some wild caught acaras and they're stunning!
Pointed face.. Rivulatus have pointed faces, pulcher are more rounded
Orange tipped fins Rivulatus have this, Pulcher RARELY do!
Eye/chin stripe... Pulcher characteristic... Rivulatus lack this usually
Vertical stripes... Pulcher have this when they're in a "normal" mood, Rivulatus only have them stressed