What are "executive members" of a conference or journal?
These conferences typically have an Executive Committee, consisting of the Chairs of the various threads in the conference. Some typical examples are the Conference Chair, Program Chair, Tutorials Chair, Posters Chair, Educator's Symposium Chair, etc. It will normally be around ten people and they are responsible for the overall running of the conference with each having primary responsibility for one aspect (other than the conference chair who has overall responsibility). 

This Executive Committee will meet several times in preparation for the conference, usually face to face and usually at the Conference Venue at least twice. The meetings are where problems are addressed and, hopefully, solved. 

An "area chair" may also have a co-chair to aid with their area. They might attend meetings or not, but are ready to serve if there is some issue with the chair. There may also be a few others with somewhat lesser responsibilities. They are arguably part of the Executive Committee. Doctoral Symposium Chair might fall into this category. 

The Program Chair is a special case and there is usually a Program Committee with several members. They may meet separately from the Executive Committee and are responsible for the overall program. They see that the right papers are accepted and that everything in the main program fits together by assigning papers to sessions. Again, they are arguably part of the Executive Committee.