What are the differences between the Keysight N6705A DC Power Analyzer and the N6705B DC Power Analyzer?

The N6705B mainframe has new labeling that identifies which knobs have secondary functions when you press them. For example, the trigger level button label tells you that it executes an autoscale when pressed.
There are some internal changes to some components on the front panel binding post assembly on the N6705B to support the higher precision SMU modules.
On the rear panel, the N6705B has holes with rubber gromits so that wires could be run out the rear of the unit, circumventing the front panel. These holes must be used when using the N6753A module since the front panel binding posts are not rated for 50 A.
The rear panel on the N6705B also contains two 8 pin connectors that break out the Auxiliary measurement from the N6781A module.
The N6705B mainframe does not include wiring harnesses with crimped on connectors the the N6705A offered. The connector that came with the DC power module must be used. The used must install the connector themselves. All of the wires are color coded and there is a label that includes the legend on the unit.
There is a video on YouTube showing all of these differences: Keysight N6705A/N6705B DC Power Analyzer Video