It is not clear which country the original post refers to, though from the context it seems to be the US. I am not familiar with US regulations, but I am with UK regulations as I used to teach food safety before I retired so I have added some information below.

Information on food labelling and other food safety issues can be found on the Food Standards Agency's website (click here for the labelling page). The information below has been extracted from the FSA website.

Basically foods in the UK are required to display one of two expiry dates.

Best before which is appropriate to most foods and indicates the period for which a food can reasonably be expected to retain its optimum condition (eg it will not be stale).

Use by is the required form of date mark only for those foods which are highly perishable from a microbiological point of view and which will have a product life after manufacture of a relatively short period, after which their consumption would present a risk of food poisoning.

This is pretty much standard throughout the EU as food safety rules across the EU have been harmonised in recent years.

I did a hunt around the FDA website and eventually tracked down the relevant page here. (The information is actually on the USDA website). The term "Use By" seems to mean much the same as it does here in the UK. In general it is wise to dispose of foods past their "Use By" dates on safety grounds and to dispose of foods past the "Best Before" date on quality grounds.