What is the difference between the powers of Parliament under Articles 249 and 250 when it comes to making laws on matters in the State List during a Proclamation of Emergency?
The powers of Parliament under Article 249 and Article 250 are not exactly the same when it comes to making laws on matters in the State List during a Proclamation of Emergency.

Article 249 specifically gives power to Parliament to make laws for the whole or any part of the territory of India, with respect to any matter enumerated in the State List, if a resolution is passed by two-thirds majority of its total membership. The law made under this article can operate for a maximum period of six months unless extended by another similar resolution.

Article 250, on the other hand, gives Parliament power to make laws for the whole or any part of the territory of India with respect to any matter enumerated in the State List while a Proclamation of Emergency is in operation. The law made under this article can operate for as long as the Proclamation of Emergency continues.

In both cases, if there is an inconsistency between a law made by Parliament and a law made by the Legislature of a State, the law made by Parliament prevails, and the law made by the State will be inoperative to the extent of the repugnancy while the Parliamentary law remains effective.