Bid-ask spread: bid-ask spread; Used to measure market liquidity. In general, the smaller the spread, the higher the liquidity. For example:1.3460-1.3450 =10 points (PTS). The standard bank spread is 5- 10 points.

Price difference: when opening a position, subtract the higher contract price from the lower contract price. (So the spread must be positive when the futures open, and it can be positive or negative when the futures close. )