It looks like a bit more than just a glue gun because of the way the plastic seems to cool almost instantly. I suppose they need to control the temperature very precisely.

That being said, in their video the actual "3D" drawing (i.e. in the air) seems extremely imprecise and for their eiffel tower demo they just make 2D sides that they glue together, so in this case it's probably fair to call it "just a glue gun", or rather a "stand-alone 3D printing head/glue gun".

If a glue gun has no glue, is it still a glue gun?