Normal wing feathers markings are reversed. So instead of black feathers and white/yellow edges, spangles have it the other way round: white/yellow feathers and black/ish edges. Head and neck feathers are lighter too. Throat spots are missing. Spangles can be paired with opaline mutation and then the wing feathers edges will have a body colour, rather than black. Throat black spots are missing.
Opaline violet spangle. Very light, almost absent head barring, no throat spots. Feathers of wings have body colour edges (violet)
Opaline olive green spangle. Very light, almost absent head barring, no throat spots. Feathers of wings have body colour edges (olive)
Sky blue spangle budgie. Unlike two previous opaline spangles - this one below is simply spangle (not opaline). The difference is in wing feathers. They're white with black/grey edges, not body colour.
There is another variety of Spangle mutation called: Melanistic Spangle. It introduces an increased amount of melanin pigment in the feathers of the budgie. The overall coloration can vary depending on the specific genetic factors involved, but it typically results in a darker appearance. The base body colour, such as blue or green, is intensified, and the feathers may appear deeper and richer in colour. Budgies with the Melanistic Spangle mutation retain the characteristic spangle pattern seen in regular Spangle budgies. The spangle pattern is characterised by areas of lighter coloration or "spangles" on the feathers, creating a mottled or marbled appearance. However, in Melanistic Spangle budgies, the spangles are usually darker and may blend more seamlessly with the overall coloration. The Melanistic Spangle mutation affects the pattern and coloration of the wing markings in budgies. The primary and secondary flight feathers typically have darkened edges, often appearing as thin or bold black lines. These darker wing markings create a distinctive contrast against the rest of the body coloration. So the primary difference between the normal Spangle budgie mutation and the Melanistic Spangle mutation lies in the intensity and distribution of melanin pigmentation in their feathers.
And when you pair up 2 Spangles (also knows as SF or Single Factor Spangles), you will get 25% Double Factor Spangles, that are totally white (in blue/white based birds) or totally yellow (in yellow/green based birds). They look like Albino or Lutino with few significant differences. You can find them HERE, I wrote about them under Ino mutation.