I would support both 'afghan' and 'throw,' if German speakers can agree on translations.
To me an afghan is the traditional brightly colored thing knitted out of squares of thick woolly yarn, often with zigzag edges or in a broad zigzag pattern, that older relatives kept on the back of their couch or threw over their knees in the recliner. Women used to knit them back in the days when more women worked at home and had more time for knitting. The colors weren't supposed to, and usually didn't, match anything else, they just added a (loud) touch of color to the room. I'm not sure I've ever seen one that was crocheted -- I thought crochet was more for doilies and baby booties -- but maybe I'm not entirely clear on the difference.
A throw is the modern, tasteful, lightweight-rug-like thing that's ready-made in China to harmonize with your catalogue furniture and decor from Pier 1, Crate and Barrel, or Pottery Barn. It can be knitted, perhaps with modern sort of nubbly yarn, but it can also just be fabric, perhaps a weave like a lighter-weight mat, maybe with a fringe. You can still drape it over the back of the couch, but it looks more like 2011 than 1951. (-: