They are both subsidiaries of the United Healhcare Group. In fact there are hundreds of them. (not all are AARP). The AARP added to the name just means they are Medicare plans branded under the AARP name to which UHC pays AARP royalties for the use of their name. To be eligible for a branded AARP UHC Medigap plan, one has to be a member of AARP at least for the year in which the plan was purchased.

The difference in these two are the "extra" benefits which one may offer over the other. They could even be in the same state.

The Medigap (supplemental) plans would cover the exact same things depending on the alphabet letter of the Medigap (supplemental) - those are benefits that are controlled at the federal level - so a Plan G would be the same in coverage for either.

However, one may cover "extra" benefits - I call them loss leaders - like a gym membership. These are benefits that can be pulled at their whim because they are not "contractual". The other contains different types of discounts.

AARP United Healthcare of America Ins. Co. offers define discounts.

AARP United Healthcare Insurance Company offer a wellness extras.