# Checkout vs Update
Fossil has two commands that look like they do the same thing on initial
examination, [`fossil update`][up] and [`fossil checkout`][co], but
there are several key differences:
1. `fossil checkout` aborts if there are changed files in the local
directory unless you give the `--force` option, whereas
`fossil update` merges upstream changes with your local changes.
Since Fossil tends to follow the CVS command design, and CVS
popularized the [merge on update][cvsmu] workflow, we expect that
Fossil’s update behavior is more likely to be what you want.
2. Update triggers an autosync attempt; checkout does not.
3. Several features in `fossil update` do not exist in
`fossil checkout`, so developing a habit to type `fossil up`
means you’re more likely to have the features you want at hand.
4. Inversely, the `fossil checkout --keep` feature doesn’t exist in
`fossil update`, but it’s a rarely-needed operation, so it doesn’t
provide a good reason to develop a habit of using `fossil checkout`
instead.
In summary, these are two separate commands; neither is an alias for the
other. They overlap enough that they can be used interchangeably for
some use cases, but `update` is more powerful and more broadly useful.
[co]: /help/checkout
[cvsmu]: http://web.mit.edu/gnu/doc/html/cvs_7.html#SEC37
[up]: /help/update