Acquisition:
If amazon acquire Flipkart then Amazon will dominate the market and all the decision making power will transferred to Amazon. Now amazon can change the name of Flipkart or can name it like “Flipkart (a product by Amazon)”
In this case, amazon will have almost majority market share of e-commerce, because of dominance they are not required to sell products at lesser price and incur the losses and it is the quick way to grow the business, many of the functions will be managed centrally for cost savings.
Merger:
JP Morgan + Chase = JP Morgan Chase
Vodafone + Idea = Vi
Here in this case after merger there will be no existence of Vodafone or Idea, Only company that exist after merger is Vi (Vodafone Idea)
If one company is good in branding and other company is good in production then they can come together and merge their entities and can give benefit to each other.