The Gidmeter reads a value from the CAN bus that represents the amount of energy stored in the battery which is not quite the same as state of charge (SOC). The Gidmeter was programmed to display 100% for 281 which was the highest number that was typically read from the CAN bus on fully-charged 2011 (and 2012) Leafs with little or no battery deterioration. I am not sure about 2013 and 2014 models, but my 2015 typically displays 292 (or 103.9%) when fully charged and once or twice it hit 293 (or 104.3%).
The SOC display in the dash on the 2015 is scaled to display 100% when the Leaf is fully charged. SOC is a percentage of the maximum energy the battery can store in its present condition. This means it will display 100% even if the battery capacity has dropped. With a fully-charged battery that has 80% of new capacity, the dash would display 100% on a 2015, but the Gidmeter would display 83.1% (80% of 103.9%).
Silver LEAF 2011 SL rear ended (totaled) by in-attentive driver 1/4/2015 at 50,422 miles
Silver LEAF 2015 SL purchased 2/7/2015; traded 8/10/2019 at 82,436 miles
White LEAF 2019 SL Plus purchased 8/10/2019