How to highlight differences in a pdf after comparing two pdfs?

I am trying to compare two PDFs and highlight the differences in second PDF. I could print the difference between two PDFs. So my question is how to highlight this printed text. Any pointers on this would be helpful.

for i in range(len(result_1)):
    if (result_1[i] != result_2[i]):
        print(result_2[i])