The date and the 'WE' are great helps to ID these. When you look at them side by side you will note how the reduction of the devices and even the bust figures in on the differences:
Note the space to the right on LIBERTY? The area above the head? The space tot he right on the '2' on the date? The "WE" has a huge difference between the two. Copy these images and make your own educational files for future reference.