A sketch is a drawing, generally out of pencil, chalk, pastels, crayons, etc., generally wth only one color. A portrait can range from a painting to a drawing or photograph, generally multicolored.
An isometric is more specific
The main difference is the means by which each is accomplished. A traditional illustration is a sketch, painting, drawing, etc. A photo illustration is just that - a photo.
A technical drawing is drawn precisely to a scale. Measurements taken from the drawing can be scaled up to produce or build a full size structure or machine, etc. A freehand drawing could be a simple sketch, detailed drawing, rough doodle, of a subject and is classed as a picture.
The main differences between sketch paper and drawing paper are the weight and texture. Sketch paper is lighter and has a rougher texture, making it ideal for quick sketches and experimentation. Drawing paper is heavier and smoother, providing a better surface for detailed and finished artwork.
Sketch paper is typically lighter weight and has a rougher texture, making it ideal for quick sketches and preliminary drawings. Drawing paper is heavier weight and has a smoother surface, making it better suited for detailed and finished drawings that require more precision and durability.
An isometric is more specific
Sketches are the humble beginnings of your working drawing. They are ideas put down, roughly, before you decide on your approach to the working piece. The working drawing is usually the idea decide upon and is in the process of development.
For a photograph you need a camera for a sketch you need a pad and pencil
Sketch
Artists use charcoal for drawing. The drawing is a charcoal drawing or sketch.
Cause if your gonna plan its in your head and if your gonna sketch you have to write it or draw it first