Today, we find a connection between one action with two very different implications. When you throw a goodbye kiss to a parent or beloved relative, you are expressing that you will miss them and still connect to them, even though you may not see them for a while. Even the root of the hebrew word is נשק - which means variously to be attached (תשוקה), sustained (with Yosef - ועל פיך ישק כל עמי) or kiss. All imply a longing, a connection, a caring.
So when we are told that Orpah kissed Naomi and left, whilst Rus clung to her, it just seems like two different levels - Orpah nearly made it, and Rus was just slightly better. Well done Orpah - you get a runners-up medal.
On closer examination, we realise that this was a different kiss. Orpah - as her name indicates, turned her back (ערף means the nape/back of the neck) on Naomi. Hence the midrashim which describe her return to Moav - a place of the loosest morals - in disturbing terms.
Moshe - who received an apparent kiss of death, expresses the opposite. He remains attached and we live by the Torah that he was the conduit for, 3332 years ago. That same Torah, that Rus decided to cling to. Rus, the mother of Royalty. Yet King David described himself as, 'I, your servant, son of your maidservant'. The maidservant?