Kodi is a cross-platform, open source media player available for the pi. Versions < 14.0 were called XBMC.
Kodi™ (formerly known as XBMC™) is an award-winning free and open source (GPL) software media center for playing videos, music, pictures, games, and more. Kodi runs on Linux, macOS, Windows, iOS, and Android, featuring a 10-foot user interface for use with televisions and remote controls. It allows users to play and view most videos, music, podcasts, and other digital media files from local and network storage media and the internet.
reference: About page from the Kodi website.
XBMC is the old name for what is now known as Kodi. XBMC is still the proper name if you are referring to an old version of the program (e.g., XBMC v13), but versions as of v14 and the project itself is known as Kodi.
reference: What is Kodi? What is XBMC? Intro FAQ on the Kodi wiki.
Kodi is a media player application developed by the XBMC Foundation, a non-profit technology consortium.
Two Kodi based operating systems exist for the Raspberry Pi: