Problem: While Grant does not seem to come right out and say it, I think his corporate strategies - vertical integration, and globalization are concerned with cost advantage, but diversification is associated with differentiation. Perhaps the biggest difference between a 'business strategy' and a 'corporate strategy' (as Grant refers to them) is that specific business units pursue business strategies, but more than one of the business units must be involved to pursue a corporate strategy. To be honest about, I don't think the distinction between a business strategy and a corporate strategy is significant. Do you?
Reference:
Grant, R.M. (2010). Contemporary strategy analysis. West Sussex, UK: John Wiley & Sons.