"Sell by" is generally a guide for grocers (potentially confusing for shoppers who might regard it as an expiration date)
"Best if used by" or "best before" usually refers to optimum food flavor or quality - it's not necessarily an indication that the food will be spoiled on or after that date
"Best if used by" or "best before" usually refers to optimum food flavor or quality - it's not necessarily an indication that the food will be spoiled on or after that date