Also see previous: Apache OpenOffice vs. LibreOffice
Comparing LibreOffice and Apache OpenOffice is like comparing identical twins. Even people who know them well have trouble distinguishing one from the other, and, when you find a difference, it is often trivial. All the same, the differences are growing, and LibreOffice has at least eleven advantages over OpenOffice – see the list below.
Both of these free office suites are descendants of OpenOffice.org (just don't ask in a crowd of Linux users which is true descendant of OpenOffice.org unless you're fond of flame wars). They have identical system requirements and feature sets. Both are supported by libraries of templates and extensions, and, if one acquires a new feature, the other frequently adds the feature in the next release.
However, after five years' separation, the two office suites are starting to drift apart -- and most of the increasing difference between the two is due to innovations in LibreOffice.
OpenOffice does have some features that LibreOffice lacks: a horizontal rule for web pages, a media player, and a macro recorder that is available by default rather than choice. However, many of OpenOffice's unique features are ones that LibreOffice deliberately dropped -- the horizontal rule, for instance, is only useful for designing a retro-1990s website.
By contrast, LibreOffice is steadily improving the interface and adding new features. None of these changes are revolutionary, but most of them are welcome all the same, and their effective just might be cumulative, depending on your priorities and workflow. When it’s LibreOffice vs. OpenOffice, LibreOffice is better for the following eleven reasons:
LibreOffice has devoted much of its efforts over the last few years to cleaning its code. The result? Open Hub (was Ohloh) reports that LibreOffice has 7.2 million lines of code compared to OpenOffice's 11.2 million.
You may not notice the difference when starting either office suite without a file. But open a file or save one, and the slimmed down LibreOffice is a beat or two ahead.
If you need to deal with another file format, chances are that it's Microsoft Office, which -- unfortunately -- remains the computing standard. Both LibreOffice and OpenOffice can open MSO's current format (such as a .docx text file), but only LibreOffice can save to it. Both support the old .doc format, but, since it is becoming rarer, it is the current format that matters. This extra support takes much of the pain out of filesharing.
OpenOffice.org never changed its basic editing window. Neither, so far, has OpenOffice. The main text frame and headers and footers in OpenOffice remain unchangeable rectangles unless you open File -> Page Preview.
LibreOffice, however, has reduced these basic frames to their corners. This minimal approach is enough for you to see where the frames are while getting a much stronger idea of how the printed page will look. The approach is not complete -- that wouldn't be desirable, especially for troubleshooting -- but remains much closer than what OpenOffice offers.
Comments are marginal notes for revision or collaboration. In OpenOffice, the notes are plain text. However, for those occasions when more is needed, LibreOffice allowed comments to be formatted like the main text.
OpenOffice retains OpenOffice.org's template window -- a cramped, gunmetal-gray dialogue that looks like it was designed in the 1990s, and is intimidatingly complicated.
As part of its general re-arranging of dialogue windows, LibreOffice has replaced this dinosaur with a modern looking dialogue on a white background whose function is obvious at a glance. The revision is enough to make the entire idea of templates more accessible.
The information bar is the bottom part of the editing window. It contains basic information such as the current page number and page style, and tools for adjusting the input mode and the zoom.
In OpenOffice, if you want a word or character count, you need to select Tools -> Word Count. LibreOffice makes this frequently-wanted information on the information bar, making it available at a glance.