what is a difference between column and pier?

Answer 1

I think of a pier as a support between two bridge spans. It can be made of one or more columns (or drilled shafts or piles or whatever)

columns are also what I call the supports in buildings and other structures, and I've only heard the term pier used in support of bridges or piers that jut out on the water.

Answer 2

A column in architecture and structural engineering is a vertical structural element that transmits, through compression, the weight of the structure above to other structural elements below. Other compression members are often termed columns because of the similar stress conditions. Columns can be either compounded of parts or made as a single piece. Columns are frequently used to support beams or arches on which the upper parts of walls or ceilings rest. Column in architecture refers specifically to such a structural element that also has certain proportional and decorative features

A pier is a raised walkway over water, supported by widely spread piles or pillars. The lighter structure of a pier allows tides and currents to flow almost unhindered, whereas the more solid foundations of a quay or the closely-spaced piles of a wharf can act as breakwaters, and are consequently more liable to silting. Piers can range in size and complexity from a simply lightweight wooden structure to major structures extended over a mile out to sea.

Piers have been built for several different purposes, and because these different purposes have distinct regional variances, the term pier tends to have different nuances of meaning in different parts of the world. Thus in North America and Australia, where many ports were, until recently, built on the multiple pier model, the term tends to imply a current or former cargo-handling facility. In Europe however, where ports have tended to use basins and river-side quays rather than piers, the term is principally associated with the image of a Victorian cast iron pleasure pier.

Answer 3

I think it is columns go up and piers down from ground level.