What is the difference between reorganization and reengineering

Reengineering, is seen as seeking breakthroughs in strategies and
processes, providing major improvements let's say in a business
practice. It is more in the lines of reinvention.

Reorganizations are usually a consequence of reengineering or
reinvention. Reorganizations should not be the primary reason for
reengineering efforts

A business process is a set of planned activities which are supposed
to be executed as a set of processes or steps, using a set of
organizational components such as Human Resource, Robot, Computer,
etc.

When the business process is studied and altered(some times to create
a completely different output), the activity can be called as
reengineering.

When the set of processes or steps are modified or the role of
organizational components are altered in order to obtain the same old
business process output, the activity can be called reorganization.