Adobe Acrobat vs. Adobe Acrobat Reader Tutorial

Hello, Can someone tell me what is the primary difference in Adobe Acrobat vs. Adobe Acrobat Reader. My customer was saying he was looking at a PDF file but could not fix or repair the PDF and re-save the file. Finally we discover he's on Acrobat Reader, not Adobe Acrobat Professional or Standard. I have Adobe Acrobat Professional and I'm not sure what all limitations others have who use Adobe Acrobat . . . .
Click Title Above for Additional Info. .