These changes are minor changes from the T20 system or from the official Warhammer 40k cannon for my own campaign.  I marked my own personal non-cannon changes as such. They are too small to justify their own section, so here they are.

• Jump Space is referred to as The Warp.  Otherwise the system is exactly the same as that listed in T20 with the exception that traveling the Warp without an Astropath (see new Feats) doubles the chance of a mis-jump.  See The Warp page for more detailed information.

• The Imperial Eagle and the Imperial Starburst are both symbols of the Imperium of Man (Personal Campaign Only).

• With a distrust and hatred of any AI, the highest level legal computer is High Autonomous.  The technology for AI computers and robots still exist on worlds outside the sway of man, but anyone caught with such technology within the Imperium would be summarily executed.

• Robots are illegal.  They can not be used or be owned within the Imperium of Man.  Discovery of such contraband leads to arrest and (mercifully) execution or (worse) being handed of to the Inquisition.  This of course does not mean they don't exist...

• The xenophobia of the w40k universe has been toned down for game play reasons.  Minor human races still exist and worlds of Orks for example fall under the sway of the Imperium.  They are not citizens, but nor have they been exterminated.  Exodite Eldars are also tolerated.  Both would be generally rare sights and meet with general prejudice.  This allows for the basic 3e dnd player races of Half-Orc, Elf (Eldar) and Half-Elf (Half Eldar).  It even allows for Tyranid, Dark Eldar, Chaos Marines, Neocron and even Daemon PCs.  The only way you can play a non-human race is if the character has a "dispensation" from an Inquisitor.

• W40k Humans, Orks, Goblins, Ogres, Dwarves and Eldar (and Dark Eldar) are functionally equivalent to their 3e dnd equivalents (Humans, Orcs, Goblins, Ogres, Dwarfs, Elves and Dark Elves respectively).

• Change the "Something lives in Jumps Space" in the T20 handbook from Wild Idea to ?? on pg. 353.

• Ignore any reference in the T20 book to Aslan, Hivers and other alien races.  None of these exist within the Imperium of Man as major races.  They may exist outside the Imperium or as minor races within the Imperium (DM's discretion).

• The Emperor is no longer a god, but pretty close to it.  He is the equivalent in power to the Pope and the Holy Roman Emperor during the Middle Ages of Earth.  He is still immortal (The Everman). The state religion is Catholicism (Personal Campaign Only). 

• The Ancients refers to the Ancient Slaan race (The Old Ones) that initially ruled most of the Galaxy and achieved supremely high tech levels, but were destroyed in a cataclysmic war against. the Necrons.  The Droynes from T20 or Lizardmen from MM (DM's preference) are the remnants of this race.

• Human names tend to be of Latin/Roman origin and makeup (Valerous, Maximus, Justinium etc.). You can also use the Inquisitor name generator here.