Grammatical differences: Whatsubject is singular, which is mainly used to ask about a specific individual's major or specialty. For example, "WhatsubjectdoesJohnmajorin?" What's John's major? Whatsubjects is a plural form, which is used to ask many individuals (two or more people) what subjects they are good at or like. For example, "Whatsubjectsdothestudentsenjoy?" What subjects do students like? )

Different contexts: when using whatsubject, the focus is on individuals and their professional fields. This usually involves academic background, professional direction or specific skills. When using whatsubjects, the focus is on groups and their respective preferences or specialties. This is usually used for broader discussions or surveys, such as hobbies or fields that many people are good at.