Definition of update and publish

[jisephcirspy]

I dont understand the definitions of update and publish when granting access to users. What can users do, when they have update access (what can they update), or when they have publish access (what can they publish)?
Please help me!

[Tanalex]

Update means a user can add to an existing application.  Publish means a user to publish an already created application to an existing stream.