Durable Power of Attorney and Guardianship, what is the difference?

I became guardian for my dad in 2018 when he wasn't making proper decisions for himself. That was based on a recommendation from APS who had become involved at that point. Yes, I charge a very minimal fee for managing his finances but the majority of the cost is in the annual attorney fees.

Guardian is appointed but the court when someone can’t appoint someone legally on their own. They may have dementia, maybe they had a massive stroke and they cant make decisions on their own.

I have POA and I am a Trustee. When my Dad was alive and then passed I was able to handle everything on my Moms behalf. She is bedridden so she was not able to handle his affairs and mentally she just couldn't handle it.

every situation is different and sometimes the person we we are caring for has needs that change due to circumstances

When a court and guardianship are involved, you can expect that significant funds will be paid to a court appointed guardian, who does have to file reports. I've seen a few guardianship reports as well as the phenomenal amounts they charge, consistent with attorney's charges and billing, but not with the often times limitations of families.

Back in the late 1990s, I saw guardianship reports itemizing what they allegedly did (similar to the billings of attorneys and paralegals), some of which were several hundred dollars. I don't recall if that was a quarterly or semi-annual report.

So this is kind of all mixed in.
There is POA
There is Trustee of Trust
Those are two different documents.
If your parents have made you POA you act as they DIRECT you, or in their behalf for their best interests if they can no longer act for themselves.
If they remain Trustees of their Trust you can do nothing with that Trust or its assets until their deaths. But if they wish to make you not the SUCCESSOR Trustee, but the CURRENT TRUSTEE, then they, as Grantors of the Trust need to see an attorney to get papers allowing you to now manage this Trust.
A POA has powers ONLY AS GIVEN and designated by the person appointing. So if Mom and Dad say tomorrow "Sorry. Don't like you any more. Removing your POA today" they can do that. Unless and until they are no longer competent to act.
Guardianship and conservatorship mean that a court has ALREADY DECIDED they cannot act for themselves. That can't be taken from you unless through your own malfeasance.
Start with going online and looking up POA for your own State. Then look up guardianship for your own state, and conservatorship.
If you still have questions I would suggest an hour of time with an Elder Law Attorney to ask them. WELL WORTH the time and money.
Wishing you the best.

You would not have to become your parent's Guardian since you are POA.
If your parent or parents were not able to make you POA for one reason or another then you would have to have been appointed Guardian.