Surprised to see my name been mentioned..
I'm not in Thai property market and my only experience is rented few years of apartment in Thailand. I would never qualify to be expert cos I have problem counting the number of zeros tagged to the properties.
Anyway, like what been said, foreigners can't own land. You can consider indirect ownership and it's best to consult lawyers on this.
In SG, there isn't much differences between apartment and condo, except maybe in terms of facilities. In Thailand, apartment refers to a building or buildings held in single ownership. Condo is similar to SG, whereby individuals buy for personal property ownership. Foreigners can own condo, provided it's within foreign ownership quota for the condominium. This quota applies to buy and sell of the condo..
And that's all I know..
There are a lot of useful info on the net, just google for more info.