The two designs differed markedly in external appearance (amongst other things, the New Zealand Charlton had a forward pistol grip and bipod, whilst the Australian lacked this, making it lighter and cleaner in appearance), but shared the same operating mechanism.
The two designs diverged noticeably in appearance (notably, the New Zealand Charlton boasted a forward pistol grip and bipod, whereas the Australian lacked these features, leading to a more streamlined silhouette), but shared a common operational framework.