While the practical effect may be the same, there is no such understanding, unless the individual chooses to take a vow (which some do, others do not - it is a private matter and no one knows except the person involved)
The purpose of any rule is to facilitate the goal of the organization. The rule of celibacy is certainly helpful for an active priest. When however, after a few years the priest chooses to become involved with a woman, the question becomes what would be best for the mission of the Church?
Lose the services of that priest, allow marriage and keep him working, or have him keep the woman on the side? Obviously the best answer is none of the above - but except for a very few asexual, or truly committed celibates, that is not happening for the ordained heterosexual men attempting to function in a frequently gay culture? How do we best further the mission of the Church or is control and discipline more important. Where does integrity come in? Must we lose the services of the priest who resigns and marries honestly? Are we better keeping the priest "celibate" and have stories like this one every week.
The priest in choosing to break his vow commits adultery against the Bride of Christ, the Church and the remedy would not be for said priest to continue in mortal sin. There are no easy answers because this is such a huge rupture of faith/truth/love.
Must we lose the services of the priest who resigns and marries honestly?
Firstly, The Church has a permanent diaconate that would suit many men that want to serve the Church as married men.
While there are certain things that can happen in life that are out of our honest control there is nothing honest in this situation. There is a big lie regarding the vow. The same is true of many a divorce.