Chemistry of transition elements: compare question

A student dissolves cobalt(II) chloride in distilled water and observes a pink solution. When concentrated hydrochloric acid is added, the solution turns blue. The student is told that the blue colour is due to the formation of a tetrachlorocobaltate(II) complex, $\ce{[CoCl4]^2-}$.

Compare the two cobalt(II) complexes with respect to the splitting of the d orbitals, the energy gap between the non-degenerate sets, the frequency of light absorbed, and the colour observed. In your answer, state which complex is octahedral and which is tetrahedral.