@Bloodline
Basically the A4000T is the redesigned version of the 4000D.
Many problems were fixed and a few new things added such as onboard SCSI plus the IDE controller.
It has rev 11 Buster and OS 3.1 (40.70) as standard, though most of the I/O, audio, GFX, chip mem, fast mem, etc is the same as the A4000D.
Zorro, video and IDE slots are mounted on the motherboard, plus you have 5 as opposed to 4 Zorro slots, making much more room for expansion.
The tower case was a standard AT style one, so you could use an off the shelf AT power supply, plus there was lots of room for drive expansion.
It had one of the "coin" type batteries for the real time clock, so you have less problems of leaking Ni-Cads which are currently causing many problems with many older models.
