Chris Holtmann and Thad Matta most certainly do not run the same offense. They both coached at Butler, which means nothing, but they come from different backgrounds and learned from entirely different people.
They both run 4-out, 1-in sets. That much is true. The concepts of spacing are similar. However, their actual plays and motion is a lot different.
Matta's offenses ran a lot of ISO and ball screens. They wanted to get defenses to switch to create matchup problems off the ball screens. If they had the ball in the post, they wanted to either force a double or kick it back out to a shooter. They would often overload one side of the floor with the best shooter and post player to keep teams from doubling.
Again, while Holtmann does run the 4-out, 1-in also, his offense is A TON more predicated on off-ball movement. They run more screening away from the ball and move guys around on the floor a lot more. See how they used Bates-Diop today... he caught the ball in a lot of different spots on the floor and a lot of different sets. Holtmann's offense has more of a 'motion' feel to it as they work the ball from side to side more. The inside-out stuff is something both Matta and Holtmann did, but Holtmann's offense is a lot more motion-based. Matta's was dribble-drive based.
It's not the same offense. Period. Some concepts are similar, but it's not the same.