LST is about like SCROG without a screen...
you would tie the main stalk down so the side branches grow up to look like colas because of the amount of light... you can then do this with the side branches depending on how long you veg...
a screen is just a way to replace all those little strings or whatever you use to tie the plant down...
either way is good shit if you are limited on vertical space... scrog makes a nice canopy though