You have a three-year transition period from the date of publication (September 2015) to move to the 2015 version. This means that, after the end of September 2018, a certificate to ISO 9001:2008 will no longer be valid.
ISO 9001:2015 specifies requirements for a quality management system when an organization:
a) needs to demonstrate its ability to consistently provide products and services that meet customer and applicable statutory and regulatory requirements, and
b) aims to enhance customer satisfaction through the effective application of the system, including processes for improvement of the system and the assurance of conformity to customer and applicable statutory and regulatory requirements.
All the requirements of ISO 9001:2015 are generic and are intended to be applicable to any organization, regardless of its type or size, or the products and services it provides.