Oral Thrush (Candidiasis): This is a common condition characterized by the overgrowth of Candida fungus in the mouth, leading to white patches on the tongue and other oral mucosal surfaces. It is often associated with pain, especially when the lesions are scraped or when eating spicy or acidic foods.

Leukoplakia: A condition where thick, white patches or lesions develop on the tongue, often due to chronic irritation. While not always painful, discomfort can occur, especially if the lesions become ulcerated or if there is an associated infection.
Lichen Planus: An autoimmune condition that can affect the mucous membranes inside the mouth, leading to white, lacy patches, and sometimes pain or discomfort, especially when eating or drinking.
Traumatic Lesions: Accidental biting of the tongue or other mechanical injuries can lead to painful lesions that may appear white due to the formation of a fibrinous pseudomembrane over the ulcer.

Oral Cancer: Although less common, any persistent, unexplained, or changing lesion on the tongue should raise suspicion for oral cancer. Early detection is crucial for effective treatment, making it a diagnosis that should not be missed, despite its lower likelihood.
Syphilis (Secondary): Oral lesions, including painless or painful white patches, can be a manifestation of secondary syphilis. Given the potential for serious complications if left untreated, syphilis should be considered in the differential diagnosis.

Hairy Leukoplakia: A rare condition seen primarily in immunocompromised patients, characterized by white patches on the lateral surfaces of the tongue that cannot be scraped off. It is associated with Epstein-Barr virus infection.
Pemphigus Vulgaris: A rare autoimmune disease that can cause blistering of the skin and mucous membranes, including the tongue, leading to painful lesions that may appear white due to secondary infection or the formation of a pseudomembrane.