Different between 1st angle projection and 3rd angle projection in drawing

There are two types of drawing in orthographic , First Angle and Third Angle. They differ only in the position of the plan, front and side views.

First angle orthographic projection  used mainly in Europe.  Third angle which is used in USA.

Orthographic 1st angle and 3rd angle Projection

First Angle Projection	Third Angle Projection
Object is imagined in 1st quadrant	Object is imagined in 3rd quadrant
Object is located between observer and plane of projection	Object is located between observer and object
the plane of projection assumed to be non transparent	the plane of projection assumed to be transparent

Learn more : orthographic  Drawing 
Learn more about with animation orthographic  Drawing