Eagle Vision:
Through out the Assassins Creed franchise Eagle vision has been a key feature that backed up the stealth aspect of the games. Eagle vision allowed for player to highlight and track enemy NPCs even through walls.
Ubisoft have scrapped eagle vision in Origins and introduced Senu – the protagonists pet eagle, that can be controlled similar to Watchdog 2’s drone and tag enemies like the Camera in the Farcry series. 
Combat:
Assassins creed combat has also had a huge overhaul in Origins. Previously combat relied on parrying NPCs attacks followed by chaining insta-kills, which enabled players to easily while out large group of enemies.
The new combat system has been described as “free form” similar to the Witcher 3: Wild Hunt, with large aspect coming from Ubisoft medieval combat game, For Honour. Combat and weapons can be upgraded similar to assassins creed: syndicate or Farcry 3
To go with the new combat style, there are new weapons as well and a shield and spear have been announced and the bow will make a return after being absent from the series since assassins creed 3.
Another huge aspect added to the combat of origins was the addition of a colosseum like arena where they can test your skills against bosses to win unique weapons or armour.
Missions:
Ubisoft announced at their E3 conference the origins was going to have the largest map yet, being 3 times larger then Black Flags map and 2 times as big as Syndicate. There are also going to be less follow missions but more side missions. There is also the return of naval combat but unlike to Assassins Creed 3 side missions instead of Black Flags base of naval combat.
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