In my experience, in the UK at least, the boundary between being accepted on to a PhD programme and accepted on to a master program is only relevant if you're right on the edge.
It does, however, make a big difference for studentships/scholarships. A great student applying for an masters place might only be an average student applying for a PhD place, so they'd get funding for a masters but not a PhD. And afterwards when that previously average PhD applicant has an MSc and is applying for a PhD, they're now a great applicant and are positioned better to get scholarships/studentships again.
If you can get a PhD place and have got enough funding to be able to afford it, take it without even considering the masters place.