A moneyline bet is the simplest wager in sports: you're just picking which team or player wins, with no point spread involved. The odds reflect each side's chance of winning.
On the moneyline you back a team to win outright. Favorites pay less than your stake (e.g. −150 / 1.67) because they're more likely to win; underdogs pay more (e.g. +150 / 2.50). The bigger the mismatch, the more lopsided the prices.
Because the moneyline is a single number per side, comparing it across books is easy and the payoff from taking the best price is direct — it's the classic market for line shopping.
Minus (−150) marks the favorite and shows the stake needed to win $100. Plus (+150) marks the underdog and shows the profit on a $100 stake.
No — it's a format. −150 = 1.67 decimal, +150 = 2.50 decimal. They express the same bet.