Storage ``from.update()`` vs ``from.upload()``

Is there any difference between the two functions? Seems like both requires

{upsert: true}

{upsert: true}

{upsert: true}

{upsert: true} to replace existing file.
What I expect from

update()

update()

update()

update() function is to be able to replace

profile.jpg

profile.jpg

profile.jpg

profile.jpg with

profile.png

profile.png

profile.png

profile.png.