There is an interest rate spread, but it's not quite that wide. Singapore doesn't offer 30 year fixed rate mortgages. The closest reasonably popular U.S. mortgage rate for comparison is the "5/1 ARM," comparable to Singapore's 5 year fixed rate mortgage. The average U.S. 5/1 ARM rate is about 5.81% according to Bankrate.com.
I have a family member who's currently paying 2.X% on a 30 year fixed rate mortgage. I think Shiny Things is also paying 2.X%. They have no interest rate risk on their mortgages. But here in Singapore we practically always have to live with interest rate risks because there's nothing past 5 years fixed.