"Use by date” is about safety
This is the most important date to remember. Foods can be eaten (and most can be frozen) up until the use by date, but not after.
You will see use by dates on food that goes off quickly, such as meat products or ready-prepared salads. For the use by to be a valid guide, you must carefully follow storage instructions.
After the use by date, don't eat it, cook it or freeze it. The food could be unsafe to eat or drink, even if it is stored correctly and looks and smells fine.
"Best before date" is about quality
Best before dates are about quality and not safety. The food will be safe to eat after this date but may not be at its best.
Its flavour and texture might not be as good. Best before dates appear on a wide range of frozen, dried, tinned and other foods and will only be accurate if the food is stored according to the instructions on the label.