Well, I see that that nidiformis often abandons its little rossetes and kinda branch out all the way around, but in my care, angelica stays in a tight rossette (very pretty). That is just in my cultivation though
Ceph is right, the D. nidiformis arms curve and sort of spread out more, where D. anglica arms are very straight, acute and upright close to the stem. The big difference is D. anglica forms a winter hibernacula in its temperate range. D. nidiformis is also more hairy, and its flowerstalk is very long and thin. D. anglica on the other hand has seed pods similar to D. intermedia on a shorter and thicker peduncle (scape). The coloration of D. nidiformis stalked glands is more orange red (in the red form) and is similar to the coloration in other South Africans, like D. aliciae. The "red" in D. anglica is quite distinctly different, and is probably what immediately distinguishes the plants to my eye. It's how they behave in my collection.