What is the difference between OpenOffice and the newly created LibreOffice?

As of now there is hardly any changes between LibreOffice and OpenOffice. The former is a fork to free OpenOffice.org from the clutches of Oracle.

Till date Sun has asked for copyright assignment to Sun if you wanted your patch to be merged. This has been a great deterrent and has limited community involvement.
LibreOffice says "Everyone is invited". It is not an office suit which will be controlled by one organization, but many organizations will take part to develop it. The supporters include Google, RedHat, Canonical, Novell and a few more (not sure about the list).

LibreOffice has also brought up a wikipage named "Easy Hacks" to get the community involved in the development. This is a great step as probably people would be excited to look at the code.

From that page I can see that the codebase is a bit messy. There are non-English comments, bogus comments, dead code and what not.

Another good reason for breaking apart was that Oracle does not look interested in taking the development of Open Source ahead. OpenSolaris is nearly gone and if this fork didn't happen, probably OO.o would also have become stagnant.

Oracle bought Sun in 2010 and commercial development of OpenOffice.org was officially terminated shortly thereafter. Then some dedicated members of the OpenOffice.org community pooled their resources and set up The Document Foundation to provide structure and leadership for the continued development of the open source code used by OpenOffice.org. The new product was named Libre Office. Most of the original OpenOffice.org community support is now behind Libre Office.

OpenOffice.org is now part of the Apache incubator project, but it still does have some licensing issues with Oracle.

Read "LibreOffice and OpenOffice.org: One Year After the Schism" to understand more.

I would personally say you should stick with using Libre Office now.

Libre Office will include the changes from Go-oo, which is the version included in Ubuntu, so I would say that Libre Office from the beginning will be more similar to Go-oo.

You can read more about the difference between OOO and Go-oo here: http://go-oo.org/