Difference between Isometric, Oblique and Orthographic Drawing

From Wikipedia.com

For Isometric reflecting that the scale along each axis of the projection is the same and it can also be seen in 3D screen editor.

For Oblique it can mean perpendicular, not straightforward, indirect or obscure.

For Orthographic projection (or orthogonal projection) is a means of representing a three dimensional object in two dimensions. It is a form of parallel projection,where the view direction is orthogonal to the projection plane, resulting in every plane of the scene appearing in affine transformation on the viewing surface. It is further divided into multiview orthographic projections and axonometric pictorials.

From Mac dictionary

Isometric1 of having equal dimensions.2 (in technical or architectural drawing) incorporating a method of showing projection or perspective in which the three principal dimensions are represented by three axes 120° apart.3 Mathematics (of a transformation) without change of shape or size.
Obliqueneither parallel nor at a right angle to a specified or implied line
Orthographic method of projection in which an object is depicted or a surface mapped using parallel lines to project its shape onto a plane.
Pictures from google search images.