Are you comparing this to ER nursing in the US?
There is a similar thread already running, which compares them, but to give a short answer, UK nurses have a lot more varied role.
We do the triage process exactly the same and draw the labs, we also do EKGs where needed and order xrays.
The main differences are that wound care is a nurse domain in the UK, and doctors just don't get involved in it.
So you will be suturing, dressing wounds and applying plaster casts.
You also do a lot more 'hands on' nursing, including diaper changing, washing and feeding patients that need assistance, and ambulating them.
These tasks form the baseline of assessments, so they are not routinely delegated.
You cannot tell someone else to bathe them and then claim to have assessed pressure areas!
The other main difference is the time factor. All patients need to be out of the A&E in four hours.
That puts a lot of pressure on you, all the way through their journey.
Triage, vitals, labs and EKG have to be done in the first 15 minutes.
All investigations must be completed and reported on by two hours.
Decision to admit or discharge by three hours, and then gone by four.
Generally nurses work at least a year on the floor before joining the ER, although I have known exceptions when they were students doing their final placement in the ER and then just sort of stayed!
Ratio is about the same, usually 4-5 patients at a time.