Your Weapon is your Smartphone.
Your Armor is your other Smartphone.
The Materia you Equip on your Smartphone is your Apps.
Weapons and Armor with Nothing Growth are iPhones.
Weapons & Armor with Normal, Double, or Triple Growth are Androids.
Growth is major updates.
Better Growth gets you major updates faster.
But you also have to think about Synergy between different Apps.
Synergy in Smartphones refers to interaction between Apps.
Synergy with Materia is called 'Materia Combos' and 'Materia Chains'.
Now try the Advanced Materia Guide.