Petaloid flowers: Petaloid means when sepals resemble petals, e.g, Lily, Anemone, Hellebore flowers etc.
Sepaloid flowers: Sepaloid means when petals resemble sepals. The data for sepaloid flower is not available. However, some flower like that of Amborella, Trimenia have green petals that resemble sepals. Thus can be considered as an example sepaloid flower.