Find the perfect aroma is the dream of all roaster. It's a daily mission because they roast the coffee every day. But there is not a perfect aroma, there are millions of them. It depends on a lot of settings from the production until the consumption.
Indeed, there are more than 200 varieties of arabica and according to the altitude, the heat, soil composition, the shading and other settings, the taste of the coffee will not be the same.
Then the process can be different, we can dry coffee beans with or without the pulp. It will gave a different taste to the coffee.
We call them natural coffee (with the pulp) or washed coffee (without). Natural coffee are generally stronger than the others. But there is no bitterness.