Everything that Tom does which Reacher would never do
1. Nearing the end, sitting in the middle of a diner with his back to half of the people in there. Reacher always sits at the back of a room where he can see everything that's going on in the room.
2. Be a stunt car driver. Reacher is not a good driver.
3. Run around all the time. Reacher is a slow runner, which fundamentally affects his tactics. He normally stands and fights.
4. (From the first movie) drop the gun just to get into a fair fist fight with the villain. Reacher always does what avoids action movie cliché, he would just shoot the guy without even a one-liner.
(Feel free to chip in)