A structure is designated as a replica of another structure when it re-uses the basic design elements of another design built previously at a different site. Such replicas are often modeled after more famous structures. They may be inexact copies, or built at a larger or smaller scale, but should be universally recognizable as replicas.

The prior design has already been built at a different site. A recognizable reuse of its basic elements can remain a replica despite changes in scale or exact detail.

A twin building instead has an almost identical neighboring counterpart. Replication concerns the recognizable relationship to an earlier design elsewhere, rather than adjacency.