Moments was done by Tetsuya Yukumi, arranged by HIKARI.
Life was composed and arranged by Yuta Nakano. It has no similarity at all to Moments, really. It has more of a SEASONS-like feel [apparently its "sister" song] and can be mashed up with it..
http://www.youtube.com/watch?v=7_Jl-ffBIDk&fmt=18 <-- abottchen's take on Life + SEASONS [former's backup, latter is melody] also known as Life of SEASONS.