New here, let me give it a try
Some terminology:
GIC and Temasek manage reserves but are not under MAS. GIC is the official SWF and Temasek is just a private company the govt owns (Temasek manage SG Govt reserves like a SWF but they don't wanna call themselves that..)
Differences between GIC's and Temasek's portfolios:
1. Geographies
GIC: no mandate, but mostly USA and Europe. See Mar 2013 geographical distribution: www . gic. com . sg/en/report/report-on-2012-2013/investment-report/geographical-distribution#.UtU4BPQW2So
Temasek: mostly Asia . See Mar 2013 geographical distribution: www . temasek. com . sg/portfolio/portfolio_highlights/geography
2. Assets
GIC: Public Equities, Bonds and Alternatives like real estate, private equity..
See Mar 2013 Asset Mix: www . gic . com . sg/en/report/report-on-2012-2013/investment-report/asset-mix#.UtU4vvQW2So]
Temasek: Mostly equities, can be private or public.. See Mar 2013 Liquidity: www . temasek . com . sg/portfolio/portfolio_highlights/liquidity]Liquidity - Portfolio Highlights - Portfolio - Temasek
Temasek owns a number of subsidiaries, e.g. Fullerton Fund Management, that have different investment philosophies and focus.. Idk why I can't find a list of the subsidiaries online, but I saw it during one of their campus recruitment presentations..
(paiseh can't post live urls cos im new here.. don't know how many posts i need before can post links)