The Seder plate is a special plate used for the holiday of Passover. There is a spot for each of the following foods; the shankbone (zeroa), the egg (baytzah), the bitter herbs (maror), the charoset (apples, nuts and wine), the vegetable (karpas) and the bitter herbs (hazeret).
The Matzah plate is used to hold the three whole maztah used for the Seder.