The use of 上 (shàng) "on/above/over" in Mandarin and English I'm interested in the the differences between English and Mandarin when they are talking about spatial preposition.

Can i assume that in Mandarin, they use the preposition 上 for most of the times disregard the spatial differences? For example, in English, there are word like "on", "above", "over", and they have different function in their spatial category, in which "on" should be higher than "above".
I think you miss the point in your attempt to understand the use of 上 to represent on, above or over.

The Chinese language proves there is no need for more than one word to do this as the necessary information is provided entirely in the context of the conversation.

For example, I am thinking of sentences that may appear difficult:

"The bird was on his head", "The bird was over his head"

Which could both be translated in Chinese to something like:
“鸟在他头上”

Out of context you may try and guess whether it is right on his head or right above his head, however it could be either.

Here are some examples of how this could be expanded (taken from Google results):


  
  有一只鸟在他头上飞过 — extended, no contact, vertical  
  
  A bird flew over his head.
  鸟在他头上做窝 — contact  
  
  A bird built a nest on his head.
  鸟在他头上飞了几圈 — extended, no contact, vertical
  
  The bird circled above his head a few times.
  


I would be interested to find an example sentence in English that can not be easily understood in context in the Chinese with the same amount of information.