Harmonics...whats the difference?

harmonics are found at nodes on the string [e.g half the string length]. the only difference between 'natural' and 'artificial' harmonics is that the whole string length is used for natural harmonics, and the length is altered by holding down a fret for artifical harmonics.

try this: rest a fretting hand finger on the string directly over the 12th fret and play the string normally, thats a natural harmonic.

then try fretting the string at the 1st fret, resting your picking hand thumb across the string over the 13th fret and plucking the string with your index finger [without moving your thumb] thats a pinch or artificial harmonic

 

It's just a difference in technique. The physics are the same. Natural harmonics are those you can play on open strings, and thus fret with your fretting hand, and artificial harmonics require some other gymnastics.

 

A natural harmonic is when you mute a harmonic node and pluck the string. They can be performed only on open strings.

An artificial harmonic is the same, except that you artificially shorten the string length by fretting, and move the node up accordingly.

A pinch harmonic refers to "pinching" the string, using the edge of your right (picking-hand) thumb, and your guitar pick. The string is muted (producing the harmonic) with your right thumb, and plucked with the pick, while your left (fretting) hand holds down the fret. A pinch harmonic can be performed on either artificial or natural harmonics. You can also do pinch harmonics using the right (plucking) hand index fingernail, instead of a pick, and still muting with your right thumb.

Here's a lesson from YouTube:

 

An artificial harmonic can also be produced by a quick tap in the sweet spot. Example: when fretting the 7th fret quickly tap and release on the 19th fret. Use a faster, lighter touch than a hammer-on/pull-off.