\[(6a - 2)^{2} - (5a + 2)^{2} =\]
\[= 36a^{2} - 24a + 4 - \left( 25a^{2} + 20a + 4 \right) =\]
\[= 36a^{2} - 24a + 4 - 25a^{2} - 20a - 4 =\]
\[= 11a^{2} - 44a = 11a(a - 4).\ \]