Hey,
It depends on how you define the error. If you mean the difference between the two you can simply do the following:
load('matlab.mat')
MyDiff = table_A.Line2 - table_A.Line1;
figure
subplot(2,1,1)
plot(x,table_A.Line1,'r', x,table_A.Line2,'g','LineWidth',1.5)
grid on
legend('correct','with noise')
subplot(2,1,2)
plot(x,MyDiff,'LineWidth',1.5)
grid on
ylabel('error')
xlabel('data point')
