You got me curious and did the same, post a question by using contact them at the US site last night to ask what is the difference between LR and LR-SE and why the US site "Components" Usage Guide says using LR-SE for 308WIN while the CZ site does not even lists LR-SE. Got a reply email. Copy and paste as below. 5.3 LR is the thing for 308WIN!
"The large rifle primer is the correct primer to use for reloading the 308 Win. As far as the Large Rifle Primer SE. S&B no longer is producing that and I am unsure of what the difference between them was. I have never seen them since I have been working here.
Thanks
Nick Peterson
Magtech Ammunition Company, Inc."