The two types

There are two popular subspecies of african greys. The Congo and the Timneh.

Congo African grey parrot:

• the nominate subspecies
• larger than the Timneh
• at about 33 cm (12-14 in) long and weigh around a pound
• with a white leather-like featherless mask around their eyes, a brilliant crimson-red tail that is generally only a few inches long and an all black beak
• The Congo grey parrot is found on the islands of Príncipe and Bioko and is distributed from south-eastern Ivory Coast to Western Kenya, Northwest Tanzania, Southern Democratic Republic of the Congo (DRC) and Northern Angola.
• In aviculture, it is often called a "CAG"

Timneh African grey parrot:

• smaller in size
• have a darker charcoal grey colouring, a darker maroon tail, and a light, horn-coloured area to part of the upper mandible
• endemic to the western parts of the moist Upper Guinea forests and bordering savannas of West Africa from Guinea-Bissau, Sierra Leone and Southern Mali east to at least 70 km (43 mi) east of the Bandama River in Ivory Coast.
• It is often called a "TAG"
• Timnehs are also much less expensive then congos, but still make fine companions
• As pets Timnehs begin learning to speak earlier than Congos, and are often said to be less nervous around strangers and novel situations. 

Some aviculturalists recognize a third and even a fourth subspecies, but these are not distinguishable in scientific studies.