It's easy to tell the two -- similar -- lyrics apart
from looking at the chorus.

Mudcat's DigiTrad version has this chorus:

For the youth of the heart
Is as the dew of the morning
You'll wake and it's left you
Without any warning.   


All the recorded performances I have heard,
feature this chorus instead:

O! the youth of the heart
And the dew in the morning
You wake, and they've left you
Without any warning.




Then there is the final stanza/verse of the lyric,
which changes entirely.

Mudcat/DigiTrad:
O! those sweet silver dollars, I've counted them plenty
But it's many times over I've mourned my sad fate
If you would know kisses of dew and of morning
Don't wait until noon, or you'll find it's too late



Beginning with Donald Swann, the composer of the music,
all those who record "The Youth of the Heart"
sing this final verse instead:

So all you young lovers, all ready to marry,
Remember my story, and mind what I say.
For I was a wise man, and now I am sorry:
The wisdom of winter is madness in May!