What is the main difference between day game and night game. Obviously approaching a girl at a club at night is different from approaching a girl at the mall during the day. I feel like certain openers/routines just wouldn't work as well during the day at the mall. Any advice on this?

Really the only difference is how far and how fast you can take it during the day and the situation. Make it NORMAL... meaning don't go for a kiss close in the middle of Target lol in a bar... that's fine. Even in a mall.. I've done it. But its all based on comfort levels. A mall is way less of a "sexual" environment than a club is and she is not going to expect to get hit on. What you say as your opener really doesn't matter as long as its something INTERESTING.