FactorFull is an option of Factor2 (default False). If set to False, products like (a-b) (a+b) will be replaced by a^2-b^2.
FactorFull
Factor2
False
(a-b) (a+b)
a^2-b^2
Overview, Factor2.
Factor2[(a - b) (a + b) (c + d) (c - d)]
(a2−b2)(c2−d2)\left(a^2-b^2\right) \left(c^2-d^2\right)(a2−b2)(c2−d2)
Factor2[(a - b) (a + b) (c + d) (c - d), FactorFull -> True]
(a−b)(a+b)(c−d)(c+d)(a-b) (a+b) (c-d) (c+d)(a−b)(a+b)(c−d)(c+d)