Are you explicitly defining which contour levels to plot? If you don't, the contour function automatically chooses which levels to plot, trying to get some nice round numbers. If you specify the levels, you should get the same plots:
[x,y,z] = peaks;
clev = -8:2:6;
subplot(2,2,1);
[c,h] = contour(x,y,z);
clabel(c,h);
title('ft, automatic');
subplot(2,2,2);
[c,h] = contour(x,y,z*0.3048);
clabel(c,h);
title('m, automatic')
subplot(2,2,3);
[c,h] = contour(x,y,z, clev);
clabel(c,h);
title('ft, explicit')
subplot(2,2,4);
[c,h] = contour(x,y,z*0.3048, clev*0.3048);
clabel(c,h);
title('m, explicit')
