If you have a bird that you think belongs to one of the budgie varieties with no markings and no body color (i.e. the bird is just white or yellow) then there are three varieties they could belong to. These are the Inos, double factor Spangle or Dark Eyed Clear. It is worth noting that these varieties may sometimes carry a little suffusion, meaning that the white bird may have a tiny sheen of blue visible in certain lights, and a green sheen on some yellow birds.
Ino is the name for the varieties that have had all the melanin (the substance that creates all the colors apart from yellow and white) removed. This means if you have a blue or grey bird you end up with a white one, and if you have a green bird you end up with a yellow one.
Albino are the white Inos, Lutinos are the yellow ones.
They have red eyes (due to the removal of the dark color from the eye) with the usual white iris ring. Their legs and feet are pink and they have silvery white cheek patches. The hens have the usual brown ceres but the males have a flesh colored cere.
To read more about them visit the Albino and Lutino page.
This variety is a combination of two pied varieties, the Recessive Pied and the Clearflight and would more accurately be called Clearflight Recessive Pied. When these two varieties are combined you get a bird that has no markings, is pure white or yellow, with silvery white cheek patches and solid dark eyes without an iris ring. The hen has the normal brown cere and the cock has a flesh colored cere.
The eye color distinguishes Dark Eyed Clears from Inos.
A double factor Spangle differs from a single factor Spangle, which you can read about here. The double factor Spangle is a plain white or yellow bird, with silvery white cheek patches, dark eyes with an iris ring and normal colored feet, legs and cere.
The difference between this variety and the two above is the dark eye with an iris ring. The image to the right is a double factor Spangle cock.
You can read more about the two types of Spangle here.
Now we have covered the budgie with no markings. These can be combined with other varieties, however as all the markings have been removed you can't tell just by looking! The only way fo find out is to breed from them and see what the offspring look like. Another page.... another day....