Mind Blade Enhancements are the equivalent of bonuses to a magic weapon, and they are part of your mind blade. When you Reshape your mind blade, you can reassign them, but they’re always applicable whenever you have mind blade in hand.
Blade Skills are your equivalent of talents/exploits/discoveries/etc. They are part of you, and indicate particular skill on your part (generally skill in wielding the mind blade). They do not change when you reshape your mind blade, and can be treated more or less like a special kind of feat.