So says R+C, for the UK medical equivalent; and that's certainly how I would understand the EN term.

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Note added at 17 mins (2006-10-08 21:32:27 GMT)
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I am NOT a medical expert, but I have worked in a non-medical ancillary capacity in a major UK teaching hospital.

As I understand it, the ranks are broadly as follows:

Matron (nowadays more likely to be called nursing manager etc.)
[used to be the head of all the nursing staff in an entire hospital, or main service]
Sister [used to be a senior nurse, possibly in charge of a ward or section]
Staff Nurse [nursing team leader]
Nurse [the usual SRN qualified nurse (D.E. in FR)]
Nursing auxiliary [I think this would usually be an SEN]

This is not meant to be an authoritative breakdown of the nursing profession, but merely to give a general idea... I wil be only too happy if one of our more highly-qualified colleaguses will correct any inaccuracies!