Easter is related to Jesus' resurrection. It varies between 22nd March and 25th April. Christians go to church and thank Jesus for what He has done for them. Some also fast and watch the version of his life back in his lifetime.
Christmas is the traditional anniversary of Jesus Christ's birth on 25th of December. They may celebrate by acting out plays that describe the night baby Jesus was born. Churches have a special service to go along with the holiday. Many churches even hold a special midnight communion mass to celebrate the birth of Jesus