What did MJ mean?

Well...

When u fall in Любовь Ты get butterflies. That person is all Ты think about. It's like being HIGH. it's the most wonderful feeling (like a high)

However... When you're in love, and that loved one theta hurt или hurts you, it hurts your very and Ты cry

That's the difference :)

i would say 'falling in love' is the start...u start falling in Любовь and then Ты are in Любовь and thats 'being in love'
maybe he means it makes him high to fall in Любовь but when he is in Любовь he cries? IDK! hahaha its just a song 'high' and 'cry' rhyme ...