I was wondering how how priest that serves in the army as a chaplain would be different than a priest of a regular parish. What are the differences? Is he “loaned out” to the army? Is his contract different? Are his obligations different since it’s not a “typical” parish?
First, he remains a priest of his own diocese or religious order—that remains his place of incardination. He is on a temporary assignment (on loan) to the military Archdiocese.
The Military Archdiocese does not have any priests who are incardinated (permanent members of the archdiocese). When they retire (or otherwise leave) they return to their own diocese. They can also be recalled by their bishops at any time.
The Military Archdiocese is called an “endorsing agency” meaning that the Archdiocese certifies to the Department of Defense that a priest is spiritually qualified to be a chaplain. He then has to meet DoD requirements for the military (age, education, citizenship, etc) that apply to all chaplains. Every religious body has its own endorsing agencies and these (not the DoD) define who is spiritually qualified to be a chaplain to represent their religion. In other words, the DoD does not define the words “ordination” or “clergy” but leaves that to the endorsing agency.
His specific job in the military is going to depend on his individual assignment: for example, he might be a brigade chaplain, or a hospital chaplain, or an instructor at the Chaplain School, etc. etc.
All of the Catholic chaplains at a given location (say Fort such-and-such) then divide the Catholic ministry among themselves. A small post might have one location (ie one chapel) where Catholic Masses are held, or a large post might have several. Again, it will depend on the location.
When a chaplain is assigned to a unit, he is assigned as chaplain for everyone in that unit. So a battalion chaplain is responsible for everyone in that battalion. A brigade chaplain is responsible for the brigade as a whole and also has supervisory role over the battalion chaplains; divisions, and so on.
If a particular job is not religion-specific (like offer a prayer at the annual 4th of July picnic) then it’s done by whatever chaplain is assigned to the unit.
Every chaplain either “performs” or “provides” ministry to everyone within his particular assignment. That’s a key distinction. He “performs” ministry for those of his own religion only (see later exception). For those outside his own religion, he “provides” the ministry by somehow bringing the soldier and the appropriate chaplain together.
Contrary to what people often think (because of TV and movies) chaplains do not (repeat, do not) perform religious ceremonies outside of their own religion. A Catholic priest does Catholic Mass. A Lutheran minister does Lutheran services. A rabbi does Jewish services. Every chaplain must function as a member of his own religion.
That’s just a start. Did you have more specific questions?