The time it takes for enemies to spot a commando is slightly increased.
All Grenades and all Rifles have increased range, (The Machine gun, MP40 and Pistol have the same low range as usual.) this seems to be a precentage based change as the Commandos still have different ranges with guns. (Such as the Sniper being able to shoot the furthest and the Thief the smallest range.)
Medkits heal more and Commandos take less damage, oddly enough, this seems to have somehow accidently fixed the bug where your medkits will suddenly all rapidly be "auto-used" even from damage that should not have taken all 5 medkits to healed, so Rookie mode unintentionally fixes one of the worst bugs in the game.
The "Stop Bomb Deployment" timer has been doubled.
The Pistol kills enemies in 2 shots instead of 3.
The official FAQ is a little inaccurate so I made this, if you notice any other changes mention them.
Honestly for any newbies or even returning fans, I'd recommend starting with Rookie mode, merely not having the awful medkit bug is enough to make it my preferred way to play. (And I felt the gun ranges were too low in the original game.)
Edited by Samz, 04 September 2022 - 01:17 PM.