burble vs bubble

burble is not a noun while bubble is a noun.

Word	Noun	Adjective	Verb	Adverb
burble	No	No	Yes	No
bubble	Yes	No	Yes	No

As verbs, burble and bubble are synonyms defined as:

Other synonyms of burble include babble, guggle, gurgle, ripple.

burble (noun)	bubble (noun)
	a dome-shaped covering made of transparent glass or plastic
	an impracticable and illusory idea
	a speculative scheme that depends on unstable factors that the planner cannot control
	a hollow globule of gas (e.g., air or carbon dioxide)

burble (verb)	bubble (verb)
flow in an irregular current with a bubbling noise	expel gas from the stomach
	form, produce, or emit bubbles
	cause to form bubbles
	rise in bubbles or as if in bubbles
	flow in an irregular current with a bubbling noise