Power of Attorney is given by one person to another person. It is a way of giving a person the authority to act for you. It can be temporary and used for all sorts of reasons, but in the context of elder care it is more often a Durable POA, created in advance, which means that you can continue to act for the person even after he is no longer able to act for himself. It is, I agree, wise to get legal advice and assistance with this to make sure you're covering all the right angles.
To give someone POA, the person must be legally competent: they must be of sufficiently sound mind to understand what a POA is and what they are giving you the authority to do. It is possible for a person who has been diagnosed with Alzheimer's Disease still to be competent, if he is in the early stages; but if the disease is more advanced than that your husband may not be able to create a POA.
Guardianship is a different kettle of fish. You, for example, would apply to the courts to be appointed as your husband's guardian. The courts would have to agree a) that your husband is not able to make his own decisions; and b) that you are the best person to act for him; and they would then grant you guardianship. You would be answerable to that same court for the management of your husband's finances and welfare, and the court would give you instructions about what reports you would be required to submit to them from time to time.
Your husband has to grant someone power of attorney, guardianship comes into play when no one has been named and the court determines that a person is no longer competent. In early dementia people can still be able to understand what they are doing and are competent to get their affairs in order, the incentive to do so is one of the benefits of getting a diagnosis. Don't attempt to do this without a lawyer.
To give someone POA, the person must be legally competent: they must be of sufficiently sound mind to understand what a POA is and what they are giving you the authority to do. It is possible for a person who has been diagnosed with Alzheimer's Disease still to be competent, if he is in the early stages; but if the disease is more advanced than that your husband may not be able to create a POA.
Guardianship is a different kettle of fish. You, for example, would apply to the courts to be appointed as your husband's guardian. The courts would have to agree a) that your husband is not able to make his own decisions; and b) that you are the best person to act for him; and they would then grant you guardianship. You would be answerable to that same court for the management of your husband's finances and welfare, and the court would give you instructions about what reports you would be required to submit to them from time to time.