The Notice formats differ because they were developed before CME, CBOT and NYMEX joined together to become CME Group. CME Notices are organized according to content area, then by year, while the CBOT and NYMEX Notices are organized by year, then by content. CBOT and NYMEX also offer index files while CME Notices do not.
Note: Attached pdfs are located in the "files" folder along with the individual years.