The 7280 and 7290 are really different BBs. You can see a comparison of the two on BlackBerry.Com - here are some differences:
7290: Quad band GPRS; 7280: Tri band
7290: Bluetooth; 7280: no BT
7290: 32MB RAM; 7280: 16MB
7290 has two stage backlighting; 7280 does not
Both have color screens - not acive matrix.
Personally, there is no comparison. The 7290 is far superior to the 7280.
Screen is basically the same.