What these means in front of card model: HD, EAH and AX (tried search but didn't find answer i was looking)
They are just manufacturer codes, they aren't significant.
For example Asus ATI/AMD cards are in the format ASUS EAH6950 (E: PCI-E, A: ATI/AMD, H6950: Model HD 6950),
and Asus Nvidia cards are in the format ASUS ENGTX 580 (PCI-E, Nvidia, GTX-series, 580: Model GTX 580)
To find out if your card is reference, look at the amount of memory and the cooler. If it has a DirectCU II cooler for example and is overclocked in the factory, it's not reference.
All reference cards look alike but have different stickers on them.
Reference 6950's for instance always have 2GB of memory, a single blower fan on the right side of the card, and a dual-BIOS switch.