Low point drains are not the same, they drain the water out of the water lines inside the trailer.
Fresh water tank drain should be a small 1/4 turn plastic ball valve, probably located near your gravity water fill spout. Depending on size of your tank, it's faster just to run your water pump and a faucet into your grey tank then to drain the tank through the tank drain valve.
TT: 2015 Jayco Jayflight 26BH Elite
TV: 2014 Ram 1500 Sport, 5.7 HEMI 3.21, Firestone 1000# air suspension. WD hitch w/800# bars
SOLD: 2012 Jayco J-series 1007