Examples:
[tex](x-2)(x+2) = x^{2} -4[/tex]
~ Sum and Difference of Two Binomials (Factors) Difference of Two Squares (Product)
To get it,square the first term, and multiply the second terms.
[tex](x+2) ^{2} = x^{2} +4x+4[/tex]
~Perfect Square Trinomial(Product)
To get it, square the first term,multiply the first term and second term and multiply it again by 2 and lastly, square the last term.
I hope that helps :)