Since the first time they met, Blackbeard and Luffy’s interests have differed.
1. Food tastes are different
In chapter 223 of One Piece manga, Luffy and Blackbeard dined at the same place, Pub and Pies in Mock Town.
Since they eat in the same place, the taste of food and drinks will be similar.
This shows that what Luffy finds delicious, Blackbeard doesn’t find it delicious and vice versa.
2. Blackbeard uses the power of darkness, and Luffy eats the Sun God model devil fruit
Blackbeard’s dark darkness contrasted with Luffy’s white, making the two look like fated opponents.
3. Luffy’s adventures are not calculated, while Blackbeard seems to have a plan from the beginning
As for Blackbeard, he seems to have a long-term plan for his path.
While Luffy always seems to enjoy his adventures, Blackbeard takes every step to fulfill his plan to become Pirate King.
4. Someone commented that Luffy looks like Roger, and there are signs that Blackbeard is following in the footsteps of Rocks D. Xebec
In the Vivre Card about the Blackbeard pirates, the name of their ship is mentioned as Saber of Xebec, which can be understood as Xebec Sword.
Not only that, the headquarters of the Blackbeard gang is also located on Hachinosu pirate island.
Roger and Rocks D. Xebec were once rivals.
5. The way to choose a crew for a pirate crew is also opposite
But Blackbeard is different, he recruited dangerous criminals imprisoned in Impel Down prison such as Van Augur, Doc Q, Jesus Burgess and Laffitte,… But Blackbeard’s methods are extremely cruel.
6. Luffy is willing to sacrifice himself to help his teammates, and Blackbeard is willing to kill his teammates to get what he wants
Meanwhile, Blackbeard in the past betrayed the pirates and his teammates.
This situation shows that, if Teach is faced with a choice between his friends or his desires, he will prioritize his desires.
7. When Luffy faced death, he smiled, but when Blackbeard was threatened, he was scared
As for Luffy, he still smiles in the face of death.
Daniel 
Jackson