To me, a due date and a deadline are sometimes interchangeable but are used in slightly different ways with deadline having more urgency, emphasis and potentially quite bad consequences as a result. For instance, 'We have to meet that deadline' vs 'the due date for that book return is ____' Here, we also use due date in describing a pregnancy 'Her due date is September'. You wouldn't interchange deadline in such an example. Hope that helps.

Thought both are used interchangeably they slightly differ in meaning. Due date refers to bill payments and other more specific contexts such as child birth. Mostly used in business context, 'deadline' points out to the last date you have to deliver or turn something in.

it maybe to be deadline? one mean is time to due,other mean is last date