Summer sausage question

[Arklatex]

Is it an expiration or a sell by date? All of the ones I have purchased had a sell by date I believe.

Some just have a date printed, like this small Hillshire Farms one:



Others have a use by date, like this one from a company called Old Wisconsin:



The one above has a shelf life double what the fda site claims.

Edit: just noticed the use or freeze by printed on the Hillshire. Duh!