Difference between a semi detached and a duplex?

Sorry if this is in the wrong section.
I'm currently looking online at a house and noticed that it was connected to it's neighbour with a common wall. The listing doesn't mention anything about this, or that it is a semi detached or a duplex. It's address is a whole number and not a fraction like duplexes are. I am just wondering, perhaps mainly from a legal stand point what other considerations should I look at? How would I know if it's purely a stand alone purchase and not legally connected in anyway to the neighbour (other than the physical connection)
For example, could I put up a carport if the neighbour hasn't got one or carry out Reno's that cause the property to look different to the neighbour.

Thanks in advance.

 

What kind of title is it? terraced houses in inner city are like that

Address is not the best indicator - there are townhouses that have an address like 20 Highett Street, but are strata. A subdvision could be 1/20 or 20A but have its own title...

 

getting a survey report done is one way.

the property title and or deposited plan will indicate if it has shared walls and or any cross-easements over them (ie: party wall).

they are usually torrens title (a few old system titles still exist around the older parts of Sydney) but usually you can develop your lot independently to the adjoining lot (STCA or heritage restrictions)
you can usually paint it a different colour or put different tiles on your side of the roof, but it tends to look terrible and most seem to stay with the common colours and style.

although i have seen some shocking developments when the neighbour went to the outer limits of architectural embellishment.

 

Sydney definition:

Semi - ½ of a single storey dwelling with a shared common wall

Duplex - ½ of a 2 storey dwelling with a shared common wall or rarely one dwelling upstairs and one downstairs.

Street numbering is up to the Geographical Names Mob (or eg Oz Post) as it is dependent upon the available street number.

 

Now that is something i didn't know. I wonder if QLd is the same. I have a semi - detached (in fact 2) so i should know. In qld though, and we do all like to be different

 

States can't agree on essential things, like naming types of dwellings or beer glasses.