There are several standard types of Medigap policies, each designated with a letter: A, B, C, D, F, G, K, L, M, N. Each policy type must be the same for every insurance company, however prices can, and do differ, between companies.
A Medigap policy is different from a Medicare Advantage Plan. Those plans are ways to get Medicare, while a Medigap policy only supplements your Original Medicare benefits. Unlike Medicare Advantage Plans, you don't have to stay in network with Medigap.
New Medigap policies cannot cover prescription drugs, but policies issued prior to 2006 may be renewed. Medicare Part D came into effect in 2006, and is the way to obtain prescription drug coverage now.
Beginning in 2020, a Medigap plan that provides coverage of the Part B deductible may not be sold to a newly eligible Medicare beneficiary.