Direct HDB cost less than resale, but direct is for SGP citizens meeting eligibility criteria only. Families, single over 35, orphaned siblings, 55 yr plus for studios. Downside is that now they have to wait 2-3 years for their BTO flats or go to some outskirts.
PR's meeting some criteria and fit the racial mix inthe estate are eligible to buy resale, one per family, and you have to get rid of any private property. Resale flats can be sold by owners who have fulfilled a minimum occupation period of 5 years unless there are special circumstances.
Go to
www.hdb.gov.sg for all the info you want.
Happy HDBing :-)