Illustrator :: Text Not Identical To Text In Word Processor

I wrote the sentence "The quick brown fox jumps over a lazy dog" in Times New Roman regular 12 pt. in Illustrator CS2.  The file was saved as a pdf at "press quality."  I wrote the same sentence with the exact some font in InCopy CS2 and exported it as a pdf at press quality.  As shown in a zoomed-in screenshot from the respective pdfs, the text from Illustrator (top example below) is slightly different than the text from InCopy (bottom example below):

Is it just an unavoidable artifact of the way pdfs are rendered?  I realize it's a minor gripe, but even slight bugs/features like this would never be tolerated in a professional publishing environment.  What am I not understanding about vector images and/or pdfs?