Is this staining happening on permanent teeth?

Staining or White spots (abnormal calcification) can occur from
antibiotics (tetracycline) or high fevers as a young child. It can
also be due to 'thin' teeth- the underlying dentine showing through

Excess fluoride also causes staining

An article that links different stain color to different causes can
be found here:
http://www.medindia.net/patients/PatientInfo/toothdiscoloration.htm