if i where to say (his brain is a computer)< metaphor
(his brain is like a computer)< simlie

....Hmmmm.

Thats not a metaphor at all.

Metaphor: Josh pounced on the loose ball like a tiger.

Similie: Josh can't miss today, he's a machine.

i its a poetic rule i didnt make it but thats the way it is and has been
if u use other words
for example

(life is parallel to a cell )< metaphor
(life is similar to a cell) < metaphor
(life is like a cell)< simlie
(life is as if you where in a cell) < simlie

like and as are ruled out and will always be ruled out

yes it is because im basicly sayin his brain is a computer
get it he process things quick

buddy its the other way around

Its not the other way around tho.

yes it is because your making a similar comparison hense the name simlie

metaphor
you say one thing is another. like if you said 'my style is gravity', that's a metaphor. your style = gravity.

simile
when you say something is 'like' something or 'as' ... as something. if you said 'got honeys like sand on the beach' that's a simile, (lots of) girls = (lots of) sand on the beach

even check the totrials because ive been writing poetry since i was 13years of age and thats what everyone of my teacher say

http://community.rapverse.com/showthread.php?t=103324