Normally a needler (USA) does not design the pattern being created, but works in groups under the supervision of an embroiderer. The term 'needler' is sometimes associated with those working on large commemorative needlework projects.
'Needler' is also a Middle English term for someone who makes needles (needle-maker).
See also the TRC Needles entry on stitcher.
Source: Shorter Oxford English Dictionary: ‘Needler’.
GVE