Not really. Both allow you to compress files/folders using the settings you choose. The main difference is that if you long-tap an existing folder, you'll only be able to compress that particular folder.
With the "Create -> New Archive" option, you can select multiple folders to compress into a single archive. For example, if you have a dozen folders in a directory and want to compress five of those folders into a single archive, you'll have the option to select multiple folders.
In short, creating a new archive gives you more flexibility with what you can add. However, all the folders/files must be in the same directory. You can navigate to sub-folders during the selection process.