There is a nice Apple application called File Merge which is available as part of the Developers Software package.
The package is available as a download from the Apple Developers site, registration required but it is free for on-line only developers.
Just install the tools and you will find File Merge there.

However, if your only concern is what you posted, take a look at Transmit. It's an FTP client that does a number of things, including comparing what you have up there with what you have on your machine.

P