Hi, I was looking around a few threads, and I saw descriptions and mentions of panels, acoustic panels, bass trappers, diffusers, absorbers etc. I was wondering, what are the differences of function between these items, or are they almost the same thing?

Thanks.

Panels that use for acoustic propose called acoustic panels.
There are many type of Acoustic panels : bass trap, diffuser, absorber etc...
Bass trap abosrbs low frequency
Diffuser reflects and diffuses the sound make the sound stage wider
Absorber usually refer to the panel that absorb high and mid frequency

Oh, so bass traps and absorbers absorb sound. Is it to improve sound quality, or just to sound-proof the room?

It will be quite a lengthy explanation. Here's a link for all your questions. There are a few articles. Spend some time to read it as it is useful info.

http://www.audioholics.com/education/acoustics-principles/

Okay, read through a couple of articles there, but still a bit confused. From what I've read, the traps and absorbers reduce echos and/or reverbs? Do they also do, like, sound proofing the room or something?

Not really sure, so need clarification. Thanks!