Sekac and Smith-Pelly are each 22 and were born four days apart in June 1992.
"I see Jiri more as a player who is quick; a bit less speed, but more quick," Canadiens general manager Marc Bergevin told reporters in St. Louis on Tuesday, where the Canadiens were preparing to face the St. Louis Blues. "Those are the terms we use. From [point] A to [point] B he's really fast, but over a long distance he's not the fastest player. He's really good down low and in the corners. But in that sense I don't think we lose anything with Devante, who is not as fast. He's a big guy. He's not a speed demon, but he'll go into the tough areas and for us that was something we found attractive."
Sekac has seven goals and 16 points in 50 games. He took part in the 2015 Honda NHL All-Star Skills Competition last month.
"[Sekac] has good upside offensively. He can skate, he can shoot. He's one of those late bloomers," Ducks GM Bob Murray said.