An Anytime Goalscorer bet is a bet placed on a player to score within the 90 minutes (plus injury time) of a match. The benefit of Anytime Goal scorer betting is that your bet can be alive for the whole game. It doesn't matter if your player scores the 1st or the 10th goal just as long as they score!
The over/under, or total goals, bet involves predicting whether the total number of goals scored in a match will be over or under a specific threshold set by the bookmaker. The line may be set at 2.5 goals, and you decide whether the total goals scored by both teams will be more or less than that number.