Regarding AirAsia branches

Don't worry: it's all the same company, run to the same standards.

For legal reasons, in South-East Asia you can generally only operate flights originating from a country if you have a locally incorporated airline, so Air Asia (originally Malaysian) has a series of franchises across the continent: Thai Air Asia, Indonesia Air Asia, Air Asia Philippines, Air Asia India, Air Asia Japan, you get the idea. But procedures, maintenance etc are all standardized across the group, so this really makes very little difference to the traveler.

Air Asia, as a whole, has a pretty good safety record. It's one of Asia's largest airline groups and has been flying since 2001, with one single accident of note (Indonesia AirAsia Flight 8501). As far as I'm aware, neither the Malaysian nor the Thai affiliates have never had an accident, so I'm not sure where the difference in the score comes from: perhaps just that aviation in Thailand is generally considered more dangerous than in Malaysia.

And oh, the "AirAsia X" designation is reserved for larger planes flying longer routes, and again for legal reasons this too has to be duplicated in each country (Thai AirAsia X, Indonesia AirAsia X, etc.) This doesn't really have much bearing on safety, except to note that the X's generally fly long-distance to developed countries like Australia and Japan with very strict aviation safety procedures, meaning that they're arguably better inspected and thus safer than the domestic/short-haul non-X affiliates.

The "safety" ratings are misleading, as they factor in global situations on regional airlines.

Some of the rating points come from whether or not an airline has been certified to fly to the USA, Europe or Australia. For a regional carrier, that only flies intra-Asia, it is a huge unnecessary expense to go through the certification process for something they will never need.

So as a result you will notice that regional carriers rank lower than their international counterparts. AirAsia which is point to point within SE Asia, ranks lower because of this, while AirAsiaX which flies to Europe & Australia and thus has to be certified ranks higher. But they both are similar in terms of all other safety aspects.

AirAsia's structure is best described as a series of partnerships. Most SE Asian countries do not allow foreign ownership of a domestic airline, so Thai AirAsia, Viet Jet, Indonesia AirAsia, etc are locally owned businesses in which the parent company has a minority stake. They all follow similar operational procedures and market together under the AirAsia brand.

The same partnership system applies to AirAsia X and its Thai and Indonesia branches.

Let's try some sourced facts , shall we?

It is not true that the Air Asia airlines "procedures, maintenance etc are all standardized across the group, so this really makes very little difference to the traveler". (If I am wrong in this, I would welcome some sources to this) For example, Air Asia Indonesia had an EU ban till 2010 but not the rest. Much more importantly check this press release:

http://www.airasia.com/kh/en/press-releases/airasia-x-receives-the-iata-operational-safety-audit-iosa-registration.page

Air Asia X has completed the IATA Operational Safety Audit last year, AirAsia X Thailand has not yet.

Also the IATA recently called out the Thai government

to address urgently safety, capacity and cost issues to keep Thailand’s aviation sector competitive.

safety.

As I said elsewhere I would rather wait until the IOSA is done before I would fly this airline.