davidcole: Mortgage is a mortgage isn't it? Unless the risk is considered higher (like apartments).
Bank's will lend more on owner-occupied homes as people need somewhere to live and will try harder to keep it rather than walk away. There's also less issue of it being vacant, intentionally damaged or poorly maintained etc...
Apartments can be riskier, particularly with the bedsit (under 45m2 for one bedroom) as they are generally owned by investors rather than owner-ocuupiers. This can have an effect on the value as if the market drops, the investors (in particular the highly geared ones) are the ones that have to sell so there's often a flood of them. Likewise, if the typical purchaser is another investor then the demand for these apartments won't be high. The two combined = rock bottom prices.
Lending criteria for bare land is typically 50% for unserviced and 70-80% for serviced (i.e. water & power)