I guess maybe like me, you're using an older version of meld from a package repository. In the latest releases, it appears that the "Reload" option has been removed. Here's an excerpt from the commit comment, which explains nicely the difference between the two:
For version control and folder comparisons, Reload and Refresh already did exactly the same thing. For file comparisons, Reload actually re-reads files off disk, discarding changes if there were any. Since this behaviour is closer to that of gedit's Revert, this commit removes the Reload action for all views, and adds a Revert command to the File menu for file comparisons.