What is the difference between "light" and "slight"? How to use these words correctly in different cases?
Both words have multiple meanings, but the meanings which are synonymous would be:
light: weighing very little, or less than average.
slight: small in degree; inconsiderable.
Light is therefore a reference to weight, whereas slight refers to size, or mass. Obviously, an object's mass and weight are very different things.
When said about a person, "slight" suggests that they are thin, not very tall, or do not look very strong. We don't usually describe an object as being "slight", but we might say "a slight amount" of something, meaning little of it.
Either an object or a person could be described as "light" if it is light in weight.