hobbing machine vs miller

hobbing machine and miller both are nouns.

Word	Noun	Adjective	Verb	Adverb
hobbing machine	Yes	No	No	No
miller	Yes	No	No	No

As nouns, miller is a hypernym of hobbing machine; that is, miller is a word with a broader meaning than hobbing machine:

hobbing machine: a special type of milling machine used for gear cutting, cutting splines, and cutting sprockets.
miller: machine tool in which metal that is secured to a carriage is fed against rotating cutters that shape it

Other hypernyms of hobbing machine include milling machine, machining center.

hobbing machine (noun)	miller (noun)
a special type of milling machine used for gear cutting, cutting splines, and cutting sprockets.	any of various moths that have powdery wings
	machine tool in which metal that is secured to a carriage is fed against rotating cutters that shape it
	someone who works in a mill (especially a grain mill)