Hello!
Harlequin, also known as dominant pied, is a pied mutation that results in blotches of yellow or white color on the bird. Markings differ from bird to bird, but the head usually has more blue/green color. (Pictured left)
Pallid, sometimes known as lacewing when combined with blue, is a different mutation that lightens all of the bird's plumage quite a bit. The head is white even in juvenile and female birds, the flight feathers are greyish, and the feet are pink.
In my opinion, and it's a somewhat shaky one, the bird is a blue cinnamon opaline. Cinnamon because it's light blue and doesn't have a white head like a pallid, and opaline because of the faint markings present on the wings. However, I would suggest taking your pictures to an Indian ringneck Facebook group to get more opinions. You can also ask the breeder, though it's hit or miss if they know their own bird's mutations.