The MDA Compact IV is based on the Touch Diamond and retains its feature-set but gets a T-Mobile make-over on the case design and carrier-themed UI color skin. We can't quite tell, but it would appear that the Compact IV loses the faceted back of the Touch Diamond, a move we would applaud. Unfortunately this, and the Vario (below), are tri-band GSM devices instead of the global-friendly quad-band.
The MDA Vario IV comes as a surprise, as it is T-Mobile's variation on the yet unannounced HTC Raphael (code name). It s basically the Compact IV with side-sliding QWERTY keyboard. Other specs remain, including GPS, 3-megapixel camera and HSDPA 7.2. The Vario and Compact have identical design language, and so we guess that the Raphael will be identical to the Touch Diamond.
Last is the Ameo 16GB, an upgrade to the original Ameo and respectively the T-Mobile variation of the HTC Advantage X7510. The Ameo 16GB offers 5" large VGA touch display and detachable QWERTY keyboard. As the name implies, it offers a massive 16GB of internal storage. It has a quad-band GSM and tri-band 3G radio, allowing for true global roaming.
The Compact IV is expected to launch first, before the end of this quarter, followed by the Ameo 16GB in July and the Vario IV is last, coming to the shops at the end of the summer.
source: Mobile Phone Help Desk via Engadget