What is the difference between the -LNS and -LNJ ordering part numbers?

The LNS version is the production (secure) version of the device and the LNJ is the 'JTAG enabled' version which is used for development and included in the EV Kit.  Typically, a customer will purchase a small quantity of the LNJ version to develop their code/application.  Then, a customer will purchase the LNS version for their production build.  The LNS version is very secure since JTAG is locked and the customer code is loaded via the secure boot loader.  The data sheet of these devices usually differentiate the versions in the 'ICE' column of the ordering information table.  ICE is an acronym for In-Circuit-Emulation, which is done via the JTAG interface.