I've learnt a lot about houses in Sydney, some while property hunting, and some I learnt the hard way after moving in.
In KL, you usually buy a townhouse, that has shared walls on both sides and a tiny yard (standard widths of houses are 20 feet or 22 feet) in front. The construction is mostly the same, so all you pick is how many bedrooms you want and location. Pricing a house is much easier because all you do is see what a house sold for next door, and adjust for renovations. I longed for this simplicity when shopping for houses.
1) A large part of Sydney's terrain, especially where I live, is hilly. It's beautiful but has repercussions for house building. The high side of the street is the preferred side, because you can drive up the driveway, and it has better drainage, and better feng shui. Of these factors, drainage is the biggest issue because damp houses have many problems. You can also have a large plot of land that has little usable space because it's all on an incline.
2) A lot of Sydney's houses are old, and not well built. Old houses exist in KL, but they are usually torn down for new developments, so most houses are brick and concrete houses, with internal piping and full brick internal walls. This is easier done in Malaysia, because of the lower cost of building houses, mainly due to the much cheaper (usually imported) labour cost. Here, the cost of building lends many on a budget to using cheaper materials, and DIY-ing, some with not so great results.
Custom built houses means it's hard to know precisely what the house is made of, and precisely what standards were applied when it comes to waterproofing, insulation, etc. The older houses also have materials that you have to beware of, particularly asbestos, as this was widely used in many, many building materials.
3) There are many trees around, in front, on the road, on the property adjoining your neighbour's. Trees are a factor because they can be incredibly expensive to maintain/take down (can run into 5 digits) and can affect sunlight coming into your property. Often it's not just your trees but your neighbour's, particularly if the tree is large and right by the fence.. There could also be safety issues when it comes to big gum trees that drop branches, in tragic cases, onto people.
Tree protection orders also mean that you can't chop down trees willy nilly. So if you have a large tree smack in the middle of your yard, it may be a permanent feature.
4) Termites are a fact of life in Australia and make a bad combination with the vast amount of trees, greenery and timber constructions.
5) North, east, south or west facing? This has repercussions on sunlight, and heating in summer and winter! North facing living is considered the best because it lets in most light and heat in winter, when the sun is lower in the sky, and the eaves can shade the house in summer, when the sun is higher up.