Engineering at UoM is kind of similar to doing a a B.Sci/B.Eng double degree at Monash, but with a bit more flexibility to move around initially, and a bit risky in that if you suck you might not make it into the M.Eng.
Engineering through science at UoM is nothing like the sci/eng degree at Monash. The only similarity is in first year where at both you do two eng subjects, 2 maths subjects, 2 science subjects and the difference is the breadth at melb whilst the more science at UoM.
However in second and third year, at Monash, you do an equal amount of science and engineering subjects. At UoM, you do engineering subjects, 1 maths subject and 4 breadth subjects over those 2 years. You don't get to do straight out science in most of their engineering stream. So although you would end up with a science degree and a M.Eng, you really only have an engineering degree.