What is the effect and importance of the back focal length of a lens?

For instance, if I look at these two lenses by Ricoh, they have the same focal length and aperture, but their back focal lengths differ.

What difference does that make, in layman's terms or in practice?

http://industry.ricoh.com/en/fa_security/lens/pdf/2M/FL-CC1614A-2M.pdf http://industry.ricoh.com/en/fa_security/lens/pdf/2M/FL-CC1614-2M.pdf