Refer to Rav Shimshon Raphael Hirsch who notes that there is an animal mentioned here that doesn't appear anywhere else as a sacrifice - ״עתודים״. Ordinarily the term for such a creature is "שעירים" which represents the typical goat offering. He writes that according to the Radak, "שעירים" are smaller and younger than ״עתודים״.
It seems, therefore, that the expression of "עתודים" is more appropriate as they are the biggest and strongest in the herd, always ready for a fight - as expressed best in the quote you bring in Yechezkel - "עתודי ארץ" - "Earth's chieftains"
As a result, he writes:
זוהי אפוא משמעות השלמים של חנוכת המזבח: השבט שמח לפני ה׳ בקיומו וברצונו; שכן הוא שותף עם ה׳ בעבודתו הגדולה של ה׳ בעולם (בקר), צועד בראש בני עמו שבאותו הדור (אילִם), מגן מפני אויבים מבחוץ (עתודים), ומתמסר בנאמנות להנהגת ״רועה ישראל״ (כבשים)
This is therefore the complete meaning of the dedication of the altar: the tribe rejoices before G-d in His existence and Will; For he shares with G-d in G-d's great work in the world (בקר), walks at the head of his people in that generation (אלים), protects against enemies from outside (עתודים), and loyally gives himself to the leadership of the "shepherd of Israel" (כבשים).
So it would seem אלים is representative of those that lead from the front whilst עתודים are stronger and protect from external forces.
