Difference between SE input and Diff tied to GND?

[Bootalito]

I'm using 2 of the four 4 channels of an ADS1115 in SE mode, fed from a diff amp and an invert amp(Zero drift AD8630).  Would I get better noise reduction if I used Diff, and tie the other channel to GND?  In other words, If a design is truly using SE as I am as its just the output from an opamp, would one still get better results by using differential, and tying the other pin to ground?  I'm thinking it would only matter if I wasn't using an ADS1115 breakout and the IC laid out on the PCB properly with analog on one side and digital on the other, then the GND pin is on the digital side so would be a little noiser.

In the final design when I actually put the ADS1115 on the board and separate analog and digital, should I read differential and tie the other inputs to GND?

ref: https://easyeda.com/terryjmyers/ElectronicLoad_copy-5b28df61728c46b5a8679c53269411ff

[David Hess]

You would get better results using differential mode with the other input tied to the signal ground at the source.  So for instance with a non-inverting amplifier as the source, the differential input would be tied to the output and bottom of the feedback network.  With an inverting source, the output and non-inverting input which is grounded would be used.

[Bootalito]

You would get better results using differential mode with the other input tied to the signal ground at the source.  So for instance with a non-inverting amplifier as the source, the differential input would be tied to the output and bottom of the feedback network.  With an inverting source, the output and non-inverting input which is grounded would be used.

Thanks, but I'm a bit confused.  The inverting amp in my schematic is the one measuring current over R34, going into AIN3, and its non-inverting input is tied to ground (R34, pin 3 is connected to R34 pin 1, which is ground.)  The diff amp is the one measuring voltage, going into AIN0 and is amplifying the difference between Vin+ and Vin- (which technically has a voltage negative with respect to system ground.