One key difference in the UK is that the elected House can always both initiate legislation and then override objections from the unelected House eventually, if

One key difference in the UK is that the elected House can always both initiate legislation and then override objections from the unelected House eventually, if it chooses to do so. While in theory the monarch could also block a law by denying royal assent, if they ever actually did that, we'd probably be a republic the following year. There are plenty of reasonable criticisms of our system of government and democratic processes, but in this respect we're clearly better off than some systems, including the EU.