You have it explained next to the graph, you do not even need to be answered because you had the answer next to the graph..
What does it mean when coinmarketcap graphs are like this. The orange is the btc price and the green is the usd price. When the orange is above the green, does it mean its better to buy with USD?
The price in green, is the US dollar value, and the price in orange, is the BTC value.
You can easily compared them, it means that the usd value has increased, but maybe the btc value has probably be the same.
The same happens with all the other altcoins, there is no difference if you buy with fiat or with bitcoin, it is always going to be the same.