IDing avocado type by leaf?

jakfruit etiquette says...
Yes, if you can find the book Some Avocado Varieties for Australia from CSIRO, they have pics of leaves and fruit of main types.
There are some differences in leaf shape.
Also they way the leaves are arranged and spaced is different. This leads to tree shape and size differences.
Mexican types tend to have anise scented leaves, but Mexican hybrids can also have some scent.

There are 3 races or types of Avocado,
Mexican, Guatemalan and West Indian.
The trees of these can be distinguished.
Nowadays there are hybrids of these also.

With that info you should be able to narrow it down.
Also an older grafted tree is going to be more likely a common type, not a newer variety.
Seedlings could be harder to work out.
If the tree fruits, that will help ID also.
If you are in Nth NSW or Nth QLD there are a lot of individual fruiting seedlings, with a mix of characters.