When smart layout is turned on in your PDF display options, it will sort your comments based on size instead of order in the editor to minimize white space. If your comments look different in your report editor versus report, you probably have this enabled. Comments with more than 70 characters are put at the end of the section, with comments that include multiple pictures. So if you have Smart Layout turned on, the comments will be sorted by
"less than 70 and no pictures"
"less than 70 and 1 picture"
"more than 70 or multiple pictures"
You can turn this on and off by clicking the title of the report and then into Display Options.