What is the difference between POA and living will?

Staff,
First you need to read your Mom's Power of Attorney (POA) document to see when and what events need to happen for the POA to be "activated".  Is the POA a “Durable POA”, a “Springing POA”, or a “General POA”?   A Living Will is another name for "Advance Health Directives";  not to be confused with MEDICAL-POA or HEALTH-POA.
Copy & Paste this to your browser: https://www.agingcare.com/articles/what-is-durable-power-of-attorney-140233.htm

https://info.legalzoom.com/power-attorney-vs-durable-power-attorney-20053.html

According to:  https://legal-dictionary.thefreedictionary.com/Durable+power+of+attorney
Power of Attorney
A written document in which one person (the principal) appoints another person to act as an agent on his or her behalf, thus conferring authority on the agent to perform certain acts or functions on behalf of the principal. Powers of attorney are routinely granted to allow the agent to take care of a variety of transactions for the principal, such as executing a stock power, handling a tax audit, or maintaining a safe-deposit box. A Power of Attorney generally is terminated when the principal dies or becomes incompetent, but the principal can revoke the power of attorney at any time.

A Durable Power of Attorney differs from a traditional power of attorney in that it continues the agency relationship beyond the incapacity of the principal. The two types of durable power of attorney are immediate and "springing." The first type takes effect as soon as the durable power of attorney is executed. The second is intended to "spring" into effect when a specific event occurs, such as the disability of the principal. Most often, durable powers of attorney are created to deal with decisions involving either property management or health care.

Versions of the durable power of attorney vary from state to state. Certain powers cannot be delegated, including the powers to make, amend, or revoke a will, change insurance beneficiaries, contract a marriage, and vote.

A medical POA is a power of attorney that allows someone to make health decisions on your behalf if you are unable to do so. It does not permit anyone to make financial decisions on your behalf. However, some durable POAs may contain authority to make medical decisions in addition to financial transactions. Others make two separate documents.

AARP Advance Directive: Creating a Living Will and Health Care Power of Attorney webswite: https://www.aarp.org/caregiving/financial-legal/info-2017/living-will-power-of-attorney.html

Also, make sure that you are listed under your Mom’s medical records for the hospital and medical clinic so that you have HIPPA access to your Mom’s medical records.

My Mom’s Durable POA states” I declare that this power of attorney shall not be affected by my disability or incapacity, and that the authority granted herein shall continue during any period while I am disabled or incapacitated.” In other words, I was able to evoke my power as Mom’s POA and sign any checks, insurance papers, required farm forms, etc. as soon as Mom went into the hospital and then was admitted to the nursing home. I did not have to prove that Mom was incompetent.

FYI about POA and Social Security:  Social Security DOES NOT accepting POAs, this website explains it very well:
https://socialsecurityintelligence.com/social-security-power-of-attorney/ 

Apparently POAs are "state-governed" and not "federally-governed". The SSA made their own regulations and require that the person who assists another person with their SSA has to be either a Guardian or a Representative Payee.
Here is the website for the publication from SSA called "A Guide For Representative Payees".

https://www.ssa.gov/pubs/EN-05-10076.pdf

Take Care of yourself. {{HUGS}} & Prayers 🙏

Why did you and your Mom do "a POA with the social worker at the hospital"?  Is your Mom in the hospital currently because of her diabetes or foot problems?

FYI POA (cont):  Since Mom owns two farms, her Durable POA gives me authorization to grant farm leases and deal with farm tenants AND to sign up for any Farm Programs with the  FSA, USDA, etc.

A living will is a written document that details a person’s wishes for medical treatment if they become unable to make their wishes known—say if they were in a coma or had dementia. A living will does not appoint anyone to make decisions for you and only applies if you’re in a coma or otherwise terminal. As an example, if I had a stroke and they determined I was brain dead, I wouldn’t want machines to keep me alive. I’d put that in my Living Will. I’d also tell my husband, who has POA for me about my wishes.

A power of attorney means you can handle the person’s affairs for them, business, legal or financial. A medical POA is a legal document that gives someone you trust to make medical decisions for you if the doctor says you are incapable of making your own decisions.

Both of these documents together are called an “advanced directive”.

What does your FIL's POA document state as a reason for activating your POA authority? 

Does the AL have a Day Care program that your FIL can attend so that he can experience the activities of the AL?  What are your FIL's objections to going to live in the AL?  Why is he refusing to go to AL and why does he need to go to AL?  I know that he has been living with you and your husband for a few month, but I can't remember if there are any specific reasons for FIL to go to AL.