Originally Posted by
shelbyfv
Not the same thing. Nipple washers help to reinforce the rim and offer a smooth surface for the spoke to turn on. Spoke washers typically refer to the washers that are at the hub for thin flanges, basically it tightens up the fit of the bend so there's less stress there and the spokes last longer.
OP, I'd go with these
https://www.wheelfanatyk.com/store/oval-rim-washer/
Personally I've never needed them, if the rim has eyelets they're meant to do the job and these won't help, they'll only work if the rim is smooth on the inside. I've only been building since 97 or 98, during that time only carbon rims ever seemed to have a recommendation for them and even then it was only a few and none of which I ever needed to build. Although there may be some rims that recommend them, I've yet to see a modern rim that does. Spoke prep the spokes and lube the nipples and the wheel will go together nicely. If I ran into a rim that required these I think I'd buy something different.