What are the differences between quantity surveying and building surveying?

I think the guy below misunderstood a little.

Quanity Surveying is concerned primarily with project cost where the number, amount, type of materials are counted and priced to provide project estaimtes, budget and cost control through the works. Generally considered to be a more mathematical role concerned with number crunching and cost

Building Surveying covers a broad spectrum of roles from measured survey and design, structural surveys, legal matters such as leases and party wall awards, contract running and site supervision etc etc. More of a site based role liasing with clients and builders.

Both are types of job within the construction industry in the UK and many Commonwealth countries.

By "quantity surveying" I assume you are referring to surveys performed to compute the volume of some material such as sand, coal, rock, etc. "Building surveying" could cover a wide range of activities, depending on what you are building. The best short answer to your question is "accuracy". Volume surveys don't need to be exact - no one really worries if there are 4,000 CYD or 4,100 CYD of sand. However, when the steel beams arrive at the construction site, the bolts in the concrete foundation better fit into the holes on the beam.