I'd have to see the terms of any proposed circuit breaker for England but, as I said, there is a massive list of things those in Northern Ireland can still do under their CB that we couldn't under lockdown, which was your original question.
Well it depends on the terms of the circuit breaker but if you run down the list of Northern Ireland's new measures, there is a lot people can still do that we couldn't under lockdown.
In short: no, any "circuit breaker" is likely to be nowhere near as stringent as the "lockdown" in England...