Johnson, a 6-foot-10 center, is the team's tallest player; Jackson, a 5-9 point guard, is its shortest, or at least tied for that distinction.
But the common denominator between the two has been their play of late, their emergences when Purdue's needed them most.
With Robbie Hummel sidelined and Purdue's shooters struggling of late, Johnson and Jackson have helped keep the Boilermakers afloat.
In Big Ten play, Johnson's been one of the league's best as just a sophomore.
In conference games, he's averaging 14.8 points and 7.9 rebounds, both team-highs, while shooting 54.2 percent and leading the Big Ten in blocks, averaging nearly two-and-a-half per game.
In his three games back since missing the Michigan game with a concussion, Jackson's averaging 7.3 points and 5.3 assists, with just six total turnovers, and playing the sort of full-court defense that's helped him maintain a starting position all season as a rookie on a veteran team.
Wednesday night, Jackson held the Big Ten's leading scorer, Penn State's Talor Battle, scoreless.
"They've (both) been consistent," Coach Matt Painter said, "and that's what you try to get from all your guys every single day in practice, every day in film, every day in walk-through … concentrate, listen, be hooked up and ready to go."
Johnson certainly has been.
In Purdue's last three games without Hummel - the Boilermakers are 1-2 in those games - he's averaged 20.3 points, including a 30-point outing in an overtime loss at Ohio State, and 9.3 rebounds.
During that time, he's largely been the Boilermakers' focal point on offense, averaging 14 shots in the last three games.
"I'm just taking shots I know I can make and staying positive," Johnson said. "I'm practicing hard and posting up stronger and getting better position."
Johnson's shown a great deal of determination this season, particularly lately, in making amends for things that haven't gone his way.
He talked in the off-season in almost apologetic tones about his freshman year, which he called an eye-opening learning experience. He's responded with an All-Big Ten-caliber - at least to date - sophomore year.
In the Big Ten season opener, he missed a free throw at the end of regulation against Illinois that likely would have won the game then and there. The game went to OT and Purdue lost.
But just three games later, he made a pair of free throws - the second one by accident - in the game's final seconds to cap a comeback win at Northwestern, then helped seal a win at Wisconsin with a few more clutch shots from the foul line.
In the second game of the Big Ten season, with Purdue playing without both Hummel and Chris Kramer, Johnson got just two rebounds in 28 minutes as the Boilermakers were destroyed on the boards in a narrow loss at Penn State.
With that in mind, Johnson grabbed 13 boards against the Lions earlier this week, almost single-handedly controlling the defensive glass during Purdue's game-deciding second-half run.
"I never forget about those kinds of things," Johnson said. "... Coach didn't have to say anything about it. It just left that feeling that I didn't want to have again. So I decided to do something about it."
Oftentimes, for the better part of this season, Johnson's been the first man on the court for shoot-arounds before both games and practices.
"I feel like I should have been doing that last year, too," Johnson said. "It seemed like as a freshman, my body was always tired. This year I'm fighting through those things better, trying to get more shots up and trying to help myself become a better basketball player."
Jackson's probably gone this season through the sort of challenges Johnson did a year ago. But if he is, it's been barely evident.
Of all the positions on the floor, point guard may be the most difficult of them for a freshman to play, particularly when he's joining a team that returns largely intact, and especially when he's being asked to play a level of defense he may not have even comprehended in high school.
But Jackson's handled it all admirably.
"As Lewis has gone along as a freshman, he's been able to play through some mistakes," Painter said. "Any time you play through your mistakes, you make improvements and get better.
"He gives us something we didn't have before and that's ultimate ball pressure and ultimate quickness. I think it's key for our team that he continues to be aggressive offensively and also put pressure on the ball."
For Jackson, there's been no substitute for experience, which he's gotten plenty of right off the bat.
"Once you get from high school, the game seems so much faster," Jackson said, "but once you get used to it, your game starts to evolve and you pick up the pace.
"At first, everything was so fast it made me feel slow," added Jackson, who's anything but. "It made me realize how to pick my spots and see angles better in the college game."
Jackson's not renowned as a score, but rather more as a pace-setter, facilitator and, now, defender at the point guard spot.
But in recent games, he's asserted himself more, attacking more off the dribble and pushing the ball in transition.
At Illinois, he scored 12 points, tying his season high; vs. Penn State, he scored Purdue's first four of its overwhelming second-half run and generated more transition opportunities than the Boilermakers had gotten the previous few games.
"Talking to Coach Painter, he's just wanted me to be more aggressive," Jackson said, "and my teammates have a lot more confidence in me. They've just told me to play my game."
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