i love Of sins and shadows 0:12
a short essay
99% of the time natural harmonics are when a harmonic is produced by left hand technique and artificial harmonics are when a harmonic is produced by right hand technique.
artificial harmonics and natural harmonics are exactly the same, they both work on the principle of standing waves, whereby creating a node causes the string to vibrate in a pattern where one side of the node vibrates at half the wavelength, and the other side vibrates a multiple of that.
in laymans terms, placing a finger lightly half way up a string (e.g 12th fret, measure it with a ruler if you want) will give you a note twice the frequency of the string vibrating naturally, e.g a 12th fret harmonic on the e string, gives an e an octave up.
If you place your finger lightly on the fifth fret of the guitar, and play the note, your finger is 1/4 of the way up the string, causing it to vibrate at twice the frequency of the 12th fret harmonic, thus playing a 5th fret harmonic on the e string will give you an e 2 octaves up. you can achieve exactly the same sound by doing a pinch harmonic on the open string with your pick 1/4 of the way down the string from the other end (around your 24th fret)
pressing firmly down on a string on a guitar effectively shortens the length of the string, you could quite easily play natural harmonics by gently resting one of your other fingers on the string to create a node, however this is cumbersome and slow and it is a lot easier to achieve these same notes by using right hand technique . most people find it easier to administer vibrato to harmonics when they are played using right hand technique as it allows them to use their left hand to bend / vibrato the notes without paying much attention, with a little practice however it is just as easy to apply vibrato or to bend natural harmonics, and a 3rd fret natural harmonic on the E string sounds beasty if you chuck it into any riff down around there.
hope that clears everything up
matt