'17 Leafs were only 30 kWh (107 mile EPA range rating) and were of "gen 1" design.
'18 Leaf would be considered gen 2 and have 40 kWh batteries w/~151 mile EPA range ratings.
https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=38428&id=39860
'18 also marked the beginning of a ton of features that were unavailable prior to model year '18. See https://usa.nissannews.com/en-US/releases/release-77b5f147884a4439bd10c4d9207f2237-us-2018-nissan-leaf-press-kit (e.g. ProPilot Assist, CarPlay, Android Auto, etc.) besides being more powerful. (110 kW or 147 hp vs. 80 kW or 107 hp).
https://usa.nissannews.com/en-US/releases/release-f6fcf40f78a54118a8a01526272638f0-us-2017-nissan-leaf-press-kit is the '17 press kit.