That is a slightly deceptive comparison. A lot of drug research is done by small companies which work on just a handful of projects betting that one will pay off. When the small company hits on a winner, they then basically sell themselves to a major company and the major company markets the drug. The small company did the actual R&D. The major company ends up paying for the R&D done by the small company on all of its projects, winners and losers. However, on the major companies books, the expense is for acquisition, not R&D, even though effectively it is an R&D driven investment.
If you watch the drug sector of the small cap market, you will see non-descript companies whose stock goes up 500, 600, or even 1000% practically overnight. They've hit a winner and will be bought out soon. The small company does not have the resources to market the drug.