"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 = |(10-11)/10| * 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 = |(200-199)/200|*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.
