the line graphs and pie charts are used for different kinds of analysis
a) pie chart : it compares the portion of one thing in a group of different things
For example out of 100 people how many have brown hairs , how many have black hairs and how many have white hairs
or
like population division out of 100 into different parts
b) line graphs: they show the relation ship between two variables
Example: effect of temperature on volume
it tells the trend in any property with respect to some other quantity or quality parameter.
