A young woman in tight pants talks to a man in the street.
A teenager in tight jeans is speaking to a guy in the middle of the road.
Young woman describes a large age range not just teenagers. The tight pants could be any material not just jeans. They could be on any part of the street not just the middle.
We have no idea if the woman is a teenager, she could be any age.
The range of what can be considered a young women beyond being  a teenager. The location in which the two speak needn't be in the middle of the road.