Are you just being thick on purpose? Any such comparison is made on a common basis. That very likely is the number of orders in the first X days after the announcement or more precisely in the first X days after it was possible to order the product (which with Macs often is the same day, for iPhones that usually starts several days after the announcements).I call bs. There is no way to exceed the total sales of the previous model that has been on the market for how many years in just a matter of days.
And the 2015 MBPs have only been available since, drumroll, 2015. Or to be precise 1.5 years, 19 months for the 13" MBP, 17 months for the 15" MBP. The 2015 13" MBP got its usual annual CPU upgrade plus 1) faster SSD, 2) Force Touch trackpad, 3) a bit larger battery. The 2015 15" MBP only got an update to the discrete CPU plus the 1) faster SSD, 2) Force Touch trackpad, 3) a bit larger battery.