10 g±1 g represents a way bigger uncertainty than 200 mL±1 mL.
If you weigh something to be 10 g±1 g, the actual mass of the object cannot be smaller than 10 g - 1g = 9 g, and bigger than 10 g + 1 g = 11 g. This will give you a percent error of (you can use either measurement because the formula uses absolute value)
% error=∣∣∣10−(10±1)10∣∣∣⋅100=∣∣∣10−1110∣∣∣⋅100=10%
If you measure something to have 200 mL±1 mL, your value cannot be smaller than 200 mL - 1 mL = 199 mL and bigger than 200 mL + 1 mL = 201 mL. In this case, the percent error will be
% error=∣∣∣200−(200±1)200∣∣∣⋅100=∣∣∣200−199200∣∣∣⋅100=0.5%
Since percent errors are best kept below 5%, the measurement that produces a 10% error is not reliable at all; however, the measurement that produced a 0.5% error is considered to be very accurate.
You will definitely have greater uncertainty about the value you've measured in the case of the 10 g±1 g measurement.
