I read up on the difference between a tagline and a slogan:
Apparently a tagline is a brief phrase that supports the brand’s mantra. It rarely changes, usually only with a re-brand, and it will speak directly with the companies primary demographic.
A slogan changes very often, as they are used in certain advertising/marketing campaigns. Because they change so often the company can reach a variety of demographics and remain current. They can say many different things about the companies ever-changing beliefs, aims, products and offers.
So in summary, the tagline will embody the company in a sentence and define an identity over a long period of time. The slogan will change to keep the company current, giving it an extra edge in a competitive market.