Adobe Acrobat 9 VS. Reader 9

Adobe Acrobat 9
Adobe Reader 9
What are the differences ?
My main concern is, which do I use for filling pdf files, and how!
Thanks
Answer #1
Adobe Reader cannot modify PDF files. Adobe Acrobat can. Somebody correct me if I am somehow mistaken…
Answer #2
http://en.wikipedia.org/wiki/Adobe_Acrobat#Version_9.0
Answer #3
Moving to Helpdesk.