craftgrrl | Modge Podge vs. Acrylic Matte Medium?

Okay, this past fall I used Modge Podge for the first time, though at this point I've only used it for marble magnets - never a collage or decoupage. So I'm not an expert or anything. But now I'm in an art class where we have to use this acrylic matte medium for a collage. It looks a lot like Modge Podge, it dries clear, it works like glue to fuse papers together. It's really intended to be mixed with paint or used as an overcoat, I think. The acrylic is supposed to be archival, but I'm not sure it would produce the same sort of layering on a surface that Modge Podge is reputed to do. I guess the only difference I can notice between it and Modge Podge is that it doesn't smell, whereas Modge Podge has this definite glue smell to it.

I have to use the acrylic matte medium for my class, but for other future projects, does anyone know the pros and cons of using one over the other? What is the difference between them?