there are too many ways to explain the difference, like hundreds road leads you to Rome. I give mine: relation is like two objects are linked by drawing a line between them. relationship is like more 3d, you draw cloud shape connection to link the two. imagine you have a relation with your cousin because of blood, simple. the relationship between you and your spouse involves much more connections, sexually, emotionally, financially ect.
to fully explain the relationship and rleation between "relation" and "relationship" is beyond my capability, ;(