Consecutively different

$\begin{aligned} S_1 &=& 1 + \dfrac{1}{4} + \dfrac{1\times 4}{4\times 8} + \dfrac{1\times 4\times 7}{4\times 8\times 12} + \dfrac{1\times 4\times 7\times 10}{4\times 8\times 12\times 16} + \ldots \\ S_2 &=& 1 + \dfrac{2}{6} + \dfrac{2\times 5}{6\times 12} + \dfrac{2\times 5\times 8}{6\times 12\times 18} + \dfrac{2\times 5\times 8\times 11}{6\times 12\times 18\times 24} + \ldots \\ \end{aligned}$

Let us define two infinite series, $S_1$ and $S_2$ as above.

What is the relationship between $S_1$ and $S_2$ ?