Acoustic and diffuser panels achieve largely the same thing, but they work in different ways.
While acoustic panels absorb energy, diffuser panels dissipate it, meaning sound is scattered when it hits the panel’s surface. By scattering the sound waves as they return to the room, you significantly lower the chances of echoing, while improving overall sound quality and speech clarity.
Acoustic panels are better at reducing background noise, while diffuser panels typically have the edge when it comes to improving sound quality and speech clarity.
You might also want to consider the aesthetics of the room when making your decision. While acoustic panels are traditionally quite simple, flat, and subtle, diffuser panels feature a lot of angles and hard edges that really make them stand out in the space. This can be a good or a bad thing, depending on your style and preferences.