As adults, we all make personal decisions for ourselves, like where we will live, what medical decisions we make, etc. When someone cannot make those decisions for themselves, they need someone to make those decisions for them; when that decision-maker is appointed by the court, they are referred to as a "Guardian". The case is called a "Guardianship", and the protected/legally disabled person is sometimes called a "ward".
When a person needs the help of another, in making business or financial decisions, and that helper is appointed by the court, we refer to that person as a "Conservator", and the relationship as a "Conservatorship".
Finally, when someone dies, their estate is referred to, pretty clearly, as a "Decedent's Estate", and in Michigan, the representative is formally called a "Personal Representative". Other states refer to this representative as an "executor", or "administrator".
Each of these representatives has an obligation to the person, or to the estate they represent. They are obligated to put the interests of the person/estate, before their own interests, and they are required to account for all funds received and spent.
All three of these representatives, be they Guardians, Conservators, or Personal Representatives (or "Estate P.R.'s" for short), are referred to as "fiduciaries". This is simply one word that describes all three persons, and as well, describes others who have a special duty of care, loyalty and honor to the persons they represent. Lawyers are also considered "fiduciaries" for their clients, whether in a probate context, or not.
In addition to these other duties (of care, loyalty & honor), another thing all of these fiduciaries have in common, is a duty to report. In Guardianships, there is an "Annual Report On The Condition of The Ward", and in Conservatorships and Decedents' Estates, there is an initial Inventory of assets, and annual accountings, which take place every year thereafter, until the Conservatorship/Decedent's Estate is closed.