There's a lot of threads on this both recently and over the last 10+ years if you search the forum. The general opinion/old stereotype with Engineering and Comp Sci is that UNSW has the strongest reputation for their faculty and academics, while UTS has a more practical focus and as such has the integrated internships program, flexible timetabling and plenty of students doing full time work (or extracurricular stuff) alongside their study.
Sydney Uni is a great university but they aren't really well known for their engineering or computer science courses, so I believe many students have a preference for the uni itself. Despite that, it seems to be a good course from what I have heard and, importantly, as Usyd + UNSW are part of Go8 it would be much less hassle to transfer between USyd <-> UNSW than UTS -> Usyd/UNSW.
Completely anecdotally, Sydney Uni don't seem to have as much industry engagement and co-op programs etc. as UNSW and UTS. The timetabling (both scheduling of classes, and inability to select your timetable as with UTS/UNSW) also complicates studying alongside work. Where I work, the software developer interns and recent graduates are almost completely split between UNSW and UTS graduates with a few students from interstate as a direct result of this.
But is it the same degree like fully, cause that's pretty decent if you can secure a great course with a lower ATAR than most other Uni would take for the same course?
ATAR cutoffs are completely a function of demand and can be heavily manipulated by bonus points programs and the like. When I started uni, UNSW had a 91 cutoff with a few bonus points on offer, UTS had a cutoff of 88 with generous bonus points schemes while Usyd (if I remember correctly) had cutoffs in the low 80s with no bonus points on offer. With the different bonus points schemes, the cutoffs were effectively not comparable.
Additionally, you'll find unis like Wollongong and ANU have much lower cutoffs than anything in Sydney which is no reflection on the quality of the course or university.
they love it, would 10/10 recommend though he wanted UNSW.
This might also come as a surprise to some people on here, but plenty of people studying engineering at UTS had the cutoffs for Usyd/UNSW. Some will be on scholarships, others have their own reasons.