In business, regionalization is a business strategy frequently employed by globalized companies to compensate for some of the problems raised by globalization.

Globalization means the transformation of businesses to employ global supply chains and sell in global markets. At its most extreme, this is exemplified by huge multinational corporations such as Apple, Toyota, Diageo, McDonald's, Proctor & Gamble, and LVMH. A major problem for globalized consumer-facing companies, though, is that consumer tastes vary by region.

McDonald's expansion into India is a typical example of how regionalization of a global company works. Cattle are sacred to the Hindu religion which strongly disapproves of slaughtering and eating them; pork is also offensive to Indian Muslims. Thus instead of selling beef hamburgers or pork breakfast sausages in India, McDonald's sells the Maharaja Mac, made with chicken patties, and has extensive vegetarian offerings made in separate meat-free kitchens. Thus is a typical example of regionalization within a globalized company.

Regionalization can also refer to administrative structures, in which corporations, instead of making all decisions in a global headquarters, devolve power to regional managers who can more swiftly respond to changing local conditions.

Since you have put this in the Business group, I assume that you are talking about these terms from an economic point of view.  From that point of view, globalization is the process of making the world's economy more integrated--the process of bringing more and more parts of the world together into one seamless economy.  Regionalization is a process that is generally similar to globalization, but can compete with it to some degree.

The main similarity is that, in both cases, there is a movement towards economic integration of more than one country.  In regionalization, you have the countries of a region (say the EU) integrate their economy.  In globalization, more than one region is involved.

Although the two are similar, regionalization can be opposed to globalization.  This occurs when a region tries to integrate itself, but then puts up barriers against the rest of the world.  This would be the situation if, for example, China and the countries of SE Asia integrated but then prevented extensive integration with the rest of the world's economy.