There are so many different types of lentils. They are also called by slightly different names in different countries. For this recipe I use green lentil, you may also see them called 'Lentilles Vertes'.
You can also use puy lentils which are darker and speckled, or you can use regular lentils which are also called brown lentils. I wouldn't recommend red or yellow varieties as they tend to become 'mushier' which isn't great for this recipe.
Whilst I've included timings for cooking below, it's probably a good idea to also look at the package instructions to make sure you cook them appropriately for whatever variety you have.