Mercy may look like this. You go speeding through town 10 mph over the speed limit, police officer pulls you over, and because he is merciful (doesn’t give you what you deserve) the police officer doesn’t give you a ticket. Instead he smiles at you and lets you drive off with a warning.
Grace may look like this. You show up late for work, you sit and text your friends all day long, and you take extra-long breaks. Because your boss is graceful (gives you what you don’t deserve) you get a raise even though you are not receiving any "Worker of the Year" awards.
Grace and Mercy. Both rely on a God that loves you more than your sin. He did what it took to stand in your place. You see when Christ came to dwell among us He was full of grace but not at the cost of not speaking truth.