What the diffence of displacement and non-displacement pile?

Answer 1

A displacement pile is one which displaces soils during installation. For instance a driven pile displaces the soil as it is being driven into the ground. A non-displacement pile is one formed by some other method, perhaps a drilled shaft, or some other installation method.

Answer 2

Displacement piles displace soil and create a void during installation, which increases the lateral soil resistance. Non-displacement piles do not displace soil and rely on friction or end-bearing to transfer loads to the surrounding soil. Displacement piles are typically used in cohesive soils, while non-displacement piles are often used in granular soils.