Does anyone know how to compare PDFs for client contract changes?

Client sent a revised 18-page contract PDF and I need every change spotted before Friday. Side-by-side reading on my laptop keeps missing small wording edits, so how do I compare the two files?

Honestly, the simplest thing is using the Compare Files tool in Adobe Acrobat if you have it. If not, I just run them through Diffchecker. It highlights every tiny text edit so you dont go cross-eyed checking 18 pages manually.