A man in orange and a man in a light blue top are walking down the street towards something.
Two mean are wearing clothes and walking
Man in orange and a man in light blue implies wearing clothes.
Two men are walking down the street, regardless of what they are wearing.  Also, in sentence two "mean" should read "men."
To say that these mean are in colors means that those are the colors of the clothes they are wearing, and they are walking.