According to to the catalogue, the 60" has a depth (front ot back) of 2.1m while the 50" only has a depth of 1.2m. They are 2.6m and 2.4m wide respectively.
So there's a massive difference between the two sizes.
Paul, that's a cracking price from J&K.
John, my 60" fits in the main compartment on my ESP quiver. It sticks out a lot though. The 50" is much more compact.