Depends how you want to compare them, but you can just normalise both and plot on the same graph if you want to remove the effect of amplitude and look only at shape.
e.g.
normEnv1 = env1 / max( env1 );
normEnv2 = env2 / max( env2 );
figure;
plot( normEnv1 );
hold on
plot( normEnv2 );
This assume the two functions are of the same length and in sync with each other in terms of the sample locations.
