Classic mode removes radar, in game store, mysicals, and sidekicks and heavy weapons spawn on the map.
Source and full notes:
http://www.unchartedthegame.com/wiki/patch-1-15-041
General
Added support for PlayStation®4 Pro
Added support for High Dynamic Range display
Improved quality of stereo audio
Multiplayer
Beta Test Playlist – Classic Mode:
Starting November 3rd, and through the weekend, you’ll have a change to jump in and try out Classic Mode
We will be trying out other variations of Classic Mode during our second Beat Test weekend on November 11th
Source and full notes:
http://www.unchartedthegame.com/wiki/patch-1-15-041