If you talk in general, both the terms Global and International marketing are used interchangeably nowadays. But if you are talking in terms of marketing theories, International Marketing was a stage in the evolution of Global Marketing. Let us see how,
Stage 1 : Domestic Marketing : Companies manufacturing products and selling those within the country itself. So, no international phenomenon at all.
Stage 2 : Export Marketing : Company starts exporting products to another countries also. This is the very basic stage of global marketing. Approach of marketer in this stage is said to be ‘ethnocentric’ because although he is selling goods to foreign countries, product development is totally based upon the taste of local customer. So, focus is still on domestic market
Stage 3 : International Marketing : Now, company starts selling products to various countries and the approach is ‘Polycentric’ i.e. making different products for different countries.
Stage 4 : Multinational Marketing : Now, in this stage, the number of countries in which the company is doing business gets bigger than that in earlier stage. And so, instead of producing different goods for different countries, company tries to identify different regions for which it can deliver same product. So, same product for countries lying in one region but different from product offered in countries of another region. e.g. a company may decide to offer same product to India, Sri lanka and Pakistan if it thinks the taste of people of these countries is same but at the same time offering different product for American countries. This approach is called ‘Regiocentric approach’.
Stage 5 : Global Marketing : This is the final stage of evolution. In this stage company really operates in a very large number of countries and for the purpose of achieving cost efficiencies it analyses the requirement and taste of customers of all the countries and come out with a single product which can satisfy the needs of all. This approach is called ‘Geocentric approach’.
So, one main difference between International and the Global marketing is the approach of marketer. A truly global company instead of offering different products to different countries (as in International Marketing), develops and offers a single product to the world.
You should note one more very interesting fact that in the early stage of Export marketing also, the company was offering a single product to each of the countries as in the final stage of Global marketing. But it was entirely different because in export marketing you produce according to taste of your country and force that on other countries but in Global approach, you take care of entire countries and develop a product which can satisfy the need of all.