Isometric Drawings:
sited from:http://www.bbc.co.uk/schools/gcsebitesize/design/images/dt_g_dmi_tp6.gif


A form of three-dimensional projection in which all of the principal planes are drawn parallel to corresponding established axes and at true dimensions; horizontals usually are drawn at 30° from the normal horizontal axes; verticals remain parallel to the normal vertical axis.
Sited from:http://wiki.answers.com/Q/What_is_isometric_drawing
Oblique Drawings:
photo from:http://www.ider.herts.ac.uk/school/courseware/graphics/images/oblique.gif
Oblique drawings are designed to show a three dimensional view of an object. It is a kind of a drawing that show
s one face of the object in true shape, but the other faces on a distorted angle. Oblique is not really a '3D' system but a 2 dimensional view of an object with 'forced depth'.
sited from:http://wiki.answers.com/Q/What_is_an_oblique_drawing
Orthographic Drawings:
photofrom:http://www.bbc.co.uk/schools/gcsebitesize/design/images/dt_g_dmi_tp9.gif
A drawing that communicates the shape and size of an object through a series of related two-dimensional views.
sited from:http://wiki.answers.com/Q/What_is_an_orthographic_drawing