The daffodils are out in full glory, the cherry trees are starting to blossom, and busloads of tourists have started appearing.
One big change moving from Sydney to Oxford is the seasonality. At a higher latitude, Oxford has shorter winter days and longer summer ones, and the presence of so much deciduous vegetation - as opposed to the most common Australian flora - makes for bigger changes in appearance. In a university town drawing undergraduate students from all over the UK (and sometimes from further abroad), the cycle of the academic year is also pronounced, since most of the undergraduates go home over the long summer break. They are replaced by tourists, who peak in July and August but can be found in reasonable numbers except in winter.
Sydney has a fair number of students and attracts a lot of tourists, too, but in proportion to its population they were not nearly so significant, even living in central Sydney near a university.