PSD for beairng faults

Hi guys, Below is a code for PSD for a good bearing and faulty bearing plotted ( showing the change ). I want to plot on the same a graph the difference between them wondering if anyone can help with it. Thanks in advances

vert_data_avg_good = (goodbear(:,1)-mean(goodbear(:,1))); [Pyy,l]=pwelch(vert_data_avg_good,hanning(512),[],[],fs); semilogy(l,Pyy,'r'); hold on; [Pxx,f]=pwelch(vert_data_avg,hanning(512),[],[],fs); semilogy(f,Pxx,'b'); legend('Good bearing', 'Faulty Inner'); title('PSD on semilog scale');

Jayson Abraham