Diffuse

Diffuse is the fastest Linux-based visual diff tool listed here on AlternativeTo, but it lacks some critical features:

1. You can't display the files on top of each other. Files are always shown side-by-side.
2. There's no word wrapping for long lines.
3. There's no way to see the differences in lines longer than the window width. Combined with 1. and 2. above, this makes the tool impossible to use for files with long lines (e.g. CSVs).
4. You can't customize the keyboard shortcuts.
5. There's no special display for moved lines. Meld's display is much nicer - it shows a bubble starting from the source line and ending on the destination line:

[Edited by dandv, June 28]

The only native Linux tool I've found to diff in under one second two CSV files that only differ in the date format. See https://sourceforge.net/p/kdiff3/bugs/217/ for details.

Diffuse is the only open source linux application that enables manual alignment. kdiff3 has the functionality, but it is less ergonomic.