First, we can use the distributive property to multiply $4$ by each term inside the parentheses:
$$
[4+(w+3z)][4-(w+3z)] = 4\cdot 4 + 4\cdot (-w) + 4\cdot (3z) + (w+3z)\cdot 4 + (w+3z)\cdot (-w) + (w+3z)\cdot (-3z)
$$
Simplifying each term, we get:
$$
= 16 - 4w +
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