Can someone help explain the difference between Flattneing a PDF in Acrobat (Flatten Preview tool) verus opening a PDF file in Photoshop and re-saving as a PDF?
Opening a PDF file in Photoshop, the entire page is converted into a bitmap image. All the separate objects (graphics, text, etc.) are lost, so saving back to PDF from Photoshop is rather useless - you'd get the same result saving as a JPEG.
Flattening in Acrobat converts come types of content into others. There are two meanings for the term 'flatten' in Acrobat: