I think that you'll find traditional eiderdowns described as 'feather duvets' these days. As most of them are intended to go inside duvet covers, you're usually restricted to just white ones. However there are some coloured ones available. e.g. Amazon.co.uk User Recommendation
A traditional eiderdown was more a puffy bedspread that went over sheets and blankets. Thinner than a duvet, usually satiny and quilted. That's my childhood memory anyway.