Perspective Projection Vs Parallel Projection

Perspective Projection	Parallel Projection
The Centre of Projection (COP) is at finite distance from the projection plane.	The Centre of Projection (COP) is at infinite distance from the projection plane.
The projectors converge to a point on a view plane. This point is called vanishing point.	The projectors are parallel.
It is defined by specifying the centre of projection.	It is defined by specifying the Direction of Projection (DOP).
It provides the realistic view of an object.	It does not provide realistic view of an object.
It does not preserve relative proportions of an object i.e. distance and angles are not preserved.	It preserves relative proportions of an object i.e. shape and scale of object remains same.
Depending upon the number of vanishing points, it is of three types- one point, two point and three point.	Depending upon the direction of projection with respect to projection plane, parallel projection is of two types- orthographic and oblique projection.
It does not provide exact distance and angle therefore, it is not used as tool of exact measurement.	It provides the accurate views of the various sides of an object and therefore it is used as a tool of exact measurement.
It is used by the artists to prepare perspective drawings of 3D objects and scenes.	It is used by architects, designers, drafters to create blueprints and scale drawings of 3D objects.