@iambecomelife. Just realised I was too busy being pedantic.
You may find it easier to obtain profiles of Leander Class ships (ie Ajax, Archilles). If so, then the main difference between it and the Sydney class was the second funnel and the Walrus seaplane instead of the Swordfish.
Externally, that's basically it. Most changes were "under the hood".
Leander:
Sydney:
Want some more photos? Go to
www.awm.gov.au and click on "Collections Database" then "Collections Search" and search for any of the three ships. HMAS Hobart will bring up some nice onboard photos. A few of HMAS Perth show an interesting camo pattern.
Hope this helps.