Digital scales and other measuring devices can be deceptive. Just
because a digital device displays, for example, one-gram increments,
it doesn't necessarily mean it is accurate to one gram. You need to
read the specifications. I have seen digital thermometers that will
display, again this is an example off the top of my head, one-degree
increments, but the specs state it is only accurate to +/- 2 degrees.
I don't have particular knowledge of the scales mentioned, but you
should read the specs. You might find some interesting information.
You might find that amient temperature affects the scale's reading as well.
Larry T