write about both of them like," my life as a modern citizen is a lot different than that of a colonist by.." and go on from their. Just use a lot of examples.
"If I had to choose whether to live today or in the Colonial times, I'd definitely choose today. Colonists had few luxuries and very hard lives,
while we have modern conveniences that make life easy." Then you can go on to write a paragraph about Colonial life and follow up with a paragraph about modern life. Remember that it says compare and contrast, so you have to look for similarities as well as differences.