In Thai cooking, for curries I notice two different methods. One is where the coconut cream is put to boil and then the curry paste is added and rest of the ingredients are added. The other way is oil is heated up and then the paste is added and cooked and then the rest of the ingredients follow. Is there a right way,does the dish come out different.
The second method is FAR more preferable. When you add the curry paste to hot oil on the pan, it releases a lot more of the flavour & aromas, and also cooks out the raw-ness of many of the harsher ingredients such as onions, garlic and galangal (or ginger if you used that instead).
When you add these ingredients to boiling coconut cream, you are not releasing all the flavourss to the fullest extent because the heat that the ingredients are exposed to is significantly lower. I can imagine this being a lot more viable for pre-made curry paste (say in a can) versus curry paste from scratch. Curry made this way will be less flavoursome and aromatic.
It may also taste very strongly of onion and the coconut will be over powering. The coconut is meant to supplement the paste, which is the heart of the curry. By doing it this way, the paste is now supplementing the coconut.
There is more to it actually than just boiling the coconut milk; there is the traditional Thai technique referred to as "cracking the cream". By taking the thicker part of the coconut milk that rises to the top of the can (known in Thailand and some other places in the world as "the cream") and heating it, you can cause the fat in the cream to separate out. You can then saute the spices of the curry in that fat. I get more into it here: Why does my coconut sauce lack a strong coconut taste?
I find that technique to be preferable to any other way to make Thai curry.