Backtest Test Rules: Enter and Exit

Hi. Working in the backtester with a rebalance test. The data timeframe is 1 month, and the rebalance is monthly. I am confused about setting the entries and exits to “signal” versus “same day close” or “next day open.”

The difference in the test result when set to “signal” is enormous. When set to “signal,” the test crushes the comparison code (picture 1). When set to “next day open,” the test falls horribly short of the comparison code (picture 2).

Doesn’t make sense to me. Please explain how just those settings can make such a massive difference. Thank you.