[1][2][3][4] While some situations allow "nonconformity" and "defect" to be used synonymously, some industries distinguish between the two; a nonconformity represents a failure to meet an intended state and specification, while a defect represents a failure to meet fitness for use/normal usage requirements.
[1] Many quality management practices will do this using a relatively simple three- or four-level classification system.
[2][4] For example, U.S. federal agencies such as the National Aeronautics and Space Administration have used a simple three-tier system for quality requirements of government-acquired supplies and services: minor, major, and critical nonconformance.
An example from the automotive industry uses a 10-point system for finer granularity, where, for example, a one represents "none" (no effect), a six "moderate" (vehicle or item operable, but comfort or convenience items inoperable), and a 10 "hazardous without warning" (when a potential failure mode affects safe vehicle operation without warning).
[1] Regardless of size, these classification schemes exist to help drive discovery and correction of nonconformities (and defects).