git-stash vs. git-branch
I'm always wary of git stash. If you stash a few times, things tend to get messy. git stash list will display a numbered list of stashes you created, with messages if you provided them... But the problem lies in the fact that you can't clean up stashes except with a brutal git stash clear (which removes them all). So unless you're always consistently giving super-descriptive messages for your stashes (kinda goes against stash's philosophy), you end up with an incomprehensible bunch of stashes.
The only way I know of to figure out which one's which is to use gitk --all and spot the stashes. At least this lets you see what commit the stash was created on, as well as the diff of everything included in that stash.
Note that I'm using git 1.5.4.3, and I think 1.6 adds git stash pop, which I guess would apply the selected stash and remove it from the list. Which seems a lot cleaner.
For now, I always try to branch unless I'm absolutely positive I'm gonna get back to that stash in the same day, even within the hour.
When you restore your stash, your changes are reapplied and you continue working on your code.
To stash your current changes
$ git stash save
Saved "WIP on master: e71813e..."
You can also have more than one stash. The stash works like a stack. Every time you save a new stash, it's put on top of the stack.
$ git stash list
stash@{0}: WIP on master: e71813e..."
Note the stash@{0}
part? That's your stash ID. You'll need it to restore it later on. Let's do that right now. The stash ID changes with every stash you make. stash@{0} refers to the last stash you made.
To apply a stash
$ git stash apply stash@{0}
You may notice the stash is still there after you have applied it. You can drop it if you don't need it any more.
$ git stash drop stash@{0}
Or, because the stash acts like a stack, you can pop off the last stash you saved:
$ git stash pop
If you want to wipe all your stashes away, run the 'clear' command:
$ git stash clear
It may very well be that you don't use stashes that often. If you just want to quickly stash your changes to restore them later, you can leave out the stash ID.
$ git stash
...
$ git stash pop
Feel free to experiment with the stash before using it on some really important work.
I also have a more in-depth version of this posted on my blog.
'stash' takes the uncommitted, "dirty" stuff on your working copy, and stashes it away, leaving you with a clean working copy.
It doesn't really branch at all. You can then apply the stash on top of any other branch. Or, as of Git 1.6, you can do:
git stash branch <branchname> [<stash>]
to apply the stash on top of a new branch, all in one command.
So, stash works great if you have not committed to the "wrong" branch yet.
If you've already committed, then the workflow you describe in your question is a better alternative. And by the way, you're right: Git is very flexible, and with that flexibility comes overlapping functionality.