overall quality, age, faster trainer + nordgen (nordeus generated player 18-21 YO, always available when the server resets the day at 230ish +1)
itd be pointless for me to state their price tag, so look into your transfer market for a comparison. the most expensive youngster is always the best player/nordgen you can buy off the market

if you have lots of money and tokens, take a gamble nordgen. they will be the longest players serving your club