The F88 is actually different to the standard AUG AFAIK. Looks like they used to use normal looking A1 models but the newer Australian models have a flat rail on top with an Australian 1.5x scope IIRC. They're testing newer versions now as well.
There not the same, like Enfield did with the FN FAL they were licensed to Thale who manufactured them, improving the overall design at the same time. They look very similar but there are some subtle differences. It was not until Thale released the F88A2 variant that the rifles started looking really unique.
Working on one now just to clarify i've only replicated the A1 variant, although im looking into trying to create an A2 receiver The TM AUG A1s for some reason the bodies were modelled of the F88 but they gave them generic AUG flash hiders so you only need to pick up on of the custom beta project ones to convert it.