They are similar but not the same. Internationalisation means sell products abroad. Localization means adapt the product to the local caracteristics. So, you can internationalize without localize. But, each time more internationalisation need localization. Software industry call localization the translation and adaptation of usability to the local culture.
Hi Simon Lam, Internationalisation and localisation basically and essentially result from what we have today as the expansion of markets across the borders. But, they are not the same at all. Internationalisation is described as a process of increasing involvement of enterprises in international markets or extending production activities in many countries across the borders. The multinational and transnational companies establish their production units in several countries around the world; and by doing so, they have promoted the process of internationalisation. And when in the process of internationalisation of business activities across the border, they customise their products and services adapting to local market needs, it is known as localisation. For further details, you may use the book 1. Sthapit, Arhan (2009). International Business: Text and Cases. 2nd revised edition, Kathmandu Nepal: Taleju Prakashan, or 1. Sthapit, Arhan (2013). International Business and Environment: With Case Studies. 2nd edition, Kathmandu Nepal: Asmita Books. All the best.