Like Stabbey said:
A) You can choose to start with Ego Draconis at level 1 in Farglow
B) You can start at the beginning of Flames of Vengeance, but then with a level 35 hero.
Divinity II : The Dragon Knight Saga = complete remastered version of Ego Draconis + add-on FoV.
So in fact it is ONE (1) story, Divinity II.
This Divnity II story you can play also:
C)Start from Farglow, play whole Ego Draconis to the final battle (in the Hall of Echoes
) and IF you survive the final battle the Story continued, SEEMLESS, with Flames of Vengeance, no matter which LEVEL your hero has !!
** If I understand right (from reading on this forum), you have still all your gear (and your inventory : the Battle Tower Coffer) from Ego Draconis ! **
Good luck with the Divinity II adventure and have Fun !
** If someone know this isn't true, say it !!