Soured milk is a food product, distinguished from spoiled milk, and is a general term for milk that has acquired a tart taste, either through the addition of an acid, such as lemon juice or vinegar, or through bacterial fermentation.
Junket is a milk-based dessert, made with sweetened milk and rennet, the digestive enzyme which curdles milk. It might best be described as a custard or a very soft, sweetened cheese.