Graphical techniques are an effective means of communicating the effect of an independent variable on a dependent variable, and can lead to the determination of physical quantities.
Sketched graphs have labelled but unscaled axes, and are used to show qualitative trends, such as variables that are proportional or inversely proportional. Units generally would not need to be shown on a sketch, only the variables.
Drawn graphs have labelled and scaled axes, and are based on quantitative measurements. Drawn graphs always display the appropriate units for variables.