What is the difference between Medicare and Medicaid?

I mean Medicaid can also be applied for if a spouse is going into a NH

Medicare is medical and physician insurance for those 65 and older. Medicaid is for those of all ages who are poor. A senior can be on Medicaid and also be on Medicare if their income is low. For example, in Illinois, they have supportive living which is assisted livings for those of low income. They have the same services as a assisted living but they take Medicaid. Those people would be contributing the majority of their income to live at a supportive living and Medicaid picks up the rest. These people still have Medicare. Medicare can also be applied for if a spouse in going into a nursing home. The total assets are looked at and the community spouse (in Illinois) can keep a little over $100,000, a home and a car. Anything over that would need to be spent on the NH spouse care. There is a lot more detail but that's it in a nutshell

Medicare is for the elderly or disabled. Medicaid is for the poor. It is possible to have both!

What is the difference between medicare and Medicaid? Does one erase the other?

The difference between what, Gloria? I think part of your post got lost.