They are both independent childbirth classes - meaning they are not affiliated or accredited by any hospital, doctor or medical body. They are accredited by independent bodies.
The classes teach parents about physiological birth - i.e. what happens in your bodies on a normal healthy level. They are by no means meant to take the place of medical advice.
There is a slight difference in Amani and HypnoBirthing classes.
HypnoBirthing has been around for over 20 years and it provides techniques on harnessing the power of the mind to achieve your dream birth. The techniques include self-hypnosis, visualization, affirmations, breathing, relaxation and deepening among others. Most people will find that they carry on to use these techniques during other times in their life.
Amani is fairly new - around 4 years and focuses on providing evidence-based information to parents to help them make informed decisions during their birth. It has elements of Qur'an and hadith and the basic premise is trusting that Allah's creations are perfectly designed (backed up by evidence). This in itself is very powerful.
HypnoBirthing also provides roughly the same information. Its just that the emphasis is on the techniques and achieving the birth you want.
Both classes have the importance of shopping for the right doctor/ careprovider, the importance of a birth preference/ birth plan, your options before, during and after birth, and taking ownership of your birth.
The classes fundamentally are really quite similar in that sense - they just have a different emphasis.
Do you need to attend both classes to prepare for your pregnancy?
The short answer is no. Attending either one will usually be sufficient.
Hope this helps parents decide on which childbirth class to attend :)