The subtle use of colour helps to differentiate the two main characters in the novel.

differentiate 是动词，由前缀 dif-（表示"分开"）和词根 fer（来自拉丁语 ferre，意为"携带"）加上后缀 -ate（动词后缀）组成，字面意思是"分开携带"，引申为"区分、使不同"的意思。