What's the difference between billon and sillon?

Billon

Definition:

• (n.) An alloy of gold and silver with a large proportion of copper or other base metal, used in coinage.

Example Sentences:

Sillon

Definition:

• (n.) A work raised in the middle of a wide ditch, to defend it.

Example Sentences:

• (1) Marc Sangnier, founder of the Sillon movement at the end of the 19th century, was one of the figures emerging from that rallying cry.