Question: what is the difference between the lord day and the sabbath?
Answer: Observers of first-day worship hold that this means he was worshiping on Sunday, resurrection day. Seventh-day Sabbatarians hold that since Jesus said he was "Lord of the Sabbath" and that Isaiah called the Sabbath the "Lord's Holy Day" then the Lord's Day is the Seventh-day Sabbath (i.e. Saturday).