Yes, the curves/straight lines thing is a good distinction. Nouveau is seen as 'feminine' and deco 'masculline' (whatever that's supposed to mean!). Nouveau is also often flowery and plant-based, whereas with deco you get the ziggurart and egyptian motifs. With late deco (streamline moderne) stuff, it's all very white and sleek, often influences from the steam liner and jets (round windows, long corridors, curved walls etc) and occupies a kind of pre-modernist slot. You can see the nouveau/late deco distinction really clear if you compare the Horniman with Taymount Rise for example - really different styles.