On examining carefully, the two versions of Al Hanisim recited on Chanukah and Purim respectively, one notices that the paragraph we say on Chanukah describes in detail the military victory over the Greeks, while the Purim version omits any details of the war the Jews fight to defeat the forces of Haman.
It is somewhat ironic that the military defeats of the Greeks by the Maccabees are emphasized in relation to a conflict of Judaism versus Hellenism, a war of the spirit. On the other hand, the Purim victory over Hamanâ€™s forces is ignored, although it relates to specifically the defeat of those who wish to annihilate us physically.
While the respective military victories related to Chanukah and Purim share many parallels, in truth, the triumphs related to the Festival of Lights are not only commemorations of the defeat of a major ancient empire, but the suppression of those Hellenistic Jews whose aim and desire is to defile not only the holy Temple in Jerusalem, but the souls and spirit of the Jewish people living in Israel.
There is no doubt that the Hellenistic Jews are the majority group fully enamored and influenced by the Greek way of life, and that the Maccabees represent a small segment of devoutly pious Jews who still adhere to the commandments of G-d. The Hellenists pose more of an existential threat to the Jewish community of the time. Therefore, their defeat in addition to that of the Greek forces, receives primary attention in the Al Hanisim prayer.
On the other hand, the enemies of the Jews are not from within the community, but without. Their whole campaign against the Jews rests on the whims and actions of one man, Haman, who leads the charge in attempting to eradicate the Jewish people. Without Haman, his forces are unable to function uniformly. They are leaderless, and therefore, vulnerable to the attacks of the Jews against them. The Al Hanisim prayer hones in on the personality, Haman, who rallies his forces to attack the Jews. Without him, they are lost.
We thank G-d for all of the miracles that He has granted us, be they on Chanukah, Purim, or otherwise. The second blessing over the candles reflecting on modern and ancient miracles allows us the opportunity to recite the third blessing that G-d has kept us alive and prospering today.
Chag Urim Sameach.