I need to compare two PDF files to see differences in their text, layout, and formatting. What tools can handle both visual and text-based comparisons?

We ask the same underlying question in different ways.

• I need to compare two PDF files to see differences in their text, layout, and formatting. What tools can handle both visual and text-based comparisons?
• How can I visually verify that two PDFs have identical formatting, specifically when dealing with complex branded layouts?
• I'm looking for a tool that can perform a side-by-side visual and text comparison of two PDF documents. Which ones should I consider?