T42G better quality than T23G

[agle]

Can anybody describe to me the exact differences between T23G and T42G type phones?
They look different of course, have a different number of soft keys, etc, but what what about other key hardware differences, such as processor, RAM, speaker and handset hardware?

We are not entirely happy with the quality of our T23G phones and would like to know if we can expect better audio and higher quality calls on T42Gs.
Or are the differences more in the feature area?