Linear equations with one variable have a unique solution. The solution of a linear equation is not affected when

 the same number is added to or subtracted from both the sides of the equation
 the both sides of the equation are multiplied or divided by the same nonzero number
 Linear equation with two variables has infinitely many solutions.
 The graph of every linear equation in two variables is a straight line.
 x=0 is the equation for yaxis.
 y=0 is the equation for xaxis.
 The graph of x=a is a straight line parallel to the yaxis.
 The graph of y=a is a straight line parallel to the xaxis.
 The graph of the equation of type y=mx is a line passing through the origin.
 Every point on the graph of a linear equation in two variables is a solution of the linear equation