identify vs pick up on

identify

verb
  • To have a strong affinity with; to feel oneself to be modelled on or connected to. 

  • To disclose the identity of someone. 

  • To equate or make the same; to unite or combine into one. 

  • To claim an identity; to describe oneself as a member of a group; to assert the use of a particular term to describe oneself. 

  • To establish the identity of someone or something. 

  • To associate oneself with some group; to feel, or believe one feels, the same way. 

  • To establish the taxonomic classification of an organism. 

pick up on

verb
  • To notice, observe, learn, or understand, especially something otherwise overlooked. 

  • To adopt a practice in which others already engage. 

  • To continue or build upon (for example, a task, analysis, or narrative), beginning from a point at which someone has previously stopped. 

How often have the words identify and pick up on occurred in a corpus of books? (source: Google Ngram Viewer )