The difference is that in the beginning(Primary Coverage) has no mileage limitation (you could have 1,000,000 miles) but this perk ends on a certain date(October 31,2016).
That's when the secondary coverage begins which limits owners to 10 years from the date the vehicle was first used and is also now limited to 150,000 vehicle miles. This means that if your vehicle is over 10 years old or has more than 150,000 miles, then it no longer qualifies for this warranty extension.
The Primary Coverage offers warranty enhancement until October 31, 2016 regardless of mileage.
The Secondary Coverage is applicable for 10 years from the (DOFU) Date Of First Use or 150,000 miles, whichever occurs first.