Left top: perspective, middle: isometric

bottom: oblique, right top: orthographic

Orthographic projection is the arrangement of Plan, Side, Font or Back elevations on a 2 dimensional drawing. It shouldn't be confused with axonometric, which is a sketch with lines at 45 degrees to simulate a 3D view.

dimensional drawing. It shouldn't be confused with axonometric, which is a sketch with lines at 45 degrees to simulate a 3D view.

Isometric is a drawing method where horizontal lines are drawn at 30 degree instead, whilst vertical lines are always vertical. There is no vanishing point.

Perspective drawing, source:http://jhh.blogs.com/anthos/2006/01/add_windows_to_.html?cid=140620118

Orthographic projections are drawn to a vanishing point while Isometric projections are not and are also based on a 3 120 degree axis.

source: http://wiki.answers.com/Q/What_is_the_difference_between_Orthographic_and_Isometric_Drawings

isometric : http://www.we-r-here.com/cad_05/tutorials/level_3/3-2.htm

perspective: http://jhh.blogs.com/anthos/2006/01/add_windows_to_.html?cid=140620118

orthographic: https://www.me.utexas.edu/~rbarr/draft/Section_Views/Sectioning_Solids.html

oblique: http://www.technologystudent.com/designpro/oblique1.htm