bottleneck vs obstacle

bottleneck

noun
  • The part of a process that is too slow or cumbersome. 

  • In traffic, any narrowing of the road, especially resulting in a delay. 

  • The narrow portion that forms the pouring spout of a bottle; the neck of a bottle. 

verb
  • To slow by causing a bottleneck. 

  • To form a bottleneck. 

obstacle

noun
  • Something that impedes, stands in the way of, or holds up progress, either physically or figuratively 

How often have the words bottleneck and obstacle occurred in a corpus of books? (source: Google Ngram Viewer )