M503 printer settings why different?

I have two questions here

  1. Should out prints not be the same, are the programmed or calibrated from the factory? If not why does everyone show differences.

  2. Could I get a few setting from other users here so compare? Specifically.

my original
M203 X500.00 Y500.00 Z10.00 E20000.00
M205 B20000.00 S0.00 T0.00 X5.00 Y5.00 Z0.40 E4000.00
M851 X25.00 Y-25.00 Z-1.52 ; (mm)

another users that fixed my issues
M203 X500.00 Y500.00 Z10.00 E50.00
M205 B20000.00 S0.00 T0.00 X5.00 Y5.00 Z0.40 E10.00
851 X25.00 Y-25.00 Z-1.81 ; (mm)

and another I found online
M203 X500.00 Y500.00 Z10.00 E30.00
M205 B20000.00 S0.00 T0.00 X8.00 Y8.00 Z0.40 E5.00
M851 X25.00 Y-25.00 Z0.00 ; (mm)

Here is another
M203 X200.00 Y200.00 Z12.00 E120.00
M205 B20000.00 S0.00 T0.00 J0.01
M851 X28.00 Y-20.00 Z-2.02 ; (mm)

Is this normal? I tried calibrating with Pronterface but the ejected amount was 1000 times the amount requested. After I made the changes it was still off but working. If I did the calibration myself I would be in the negative numbers.

as for m851 I’m guessing this is done in the z leveling with the printer but not sure about m203, and 5