Differences is a menu bar app designed to quickly show the difference between two chunks of text. Working in both horizontal and vertical orientations it offers to two side-by-side text editors that offer live editing of the text you want to compare.
Unlike a full-blown diff tool, Differences is always there when you need it and requires no fumbling about putting text into files to be compared. Just copy and paste text from your writing, your source code, passages you are reviewing or log files that you are struggling to decipher. Any differences between the two panes are highlighted; any updates you make are reflected in real time.