What is the physiological difference between snorting/swallowing cocaine
You can easily google for this question and find plenty of disreputable sources, but this is another case where Wikipedia does an okay job.  There are some misleading and erroneous sentences, but this one basically sums it up:


  Compared to ingestion, the faster absorption of insufflated cocaine results in quicker attainment of maximum drug effects.


Mainly, take a look at this 1981 article.  The researchers gave participants cocaine, measured drug activity, and did then did a great review of the literature.  They found that, like plenty of other drugs, ingesting cocaine results in a slower but longer-lasting effect.

Your stomach is not an efficient route of absorption for things besides water, alcohol, and aspirin; besides, it's highly acidic.