Spread
The price difference for the same asset between two markets — in arbitrage, the entire source of profit.
In arbitrage, "spread" means the gap between the price of one asset on two different venues, quoted as a percentage of the cheaper side. A BTC perpetual at 64 000 on one exchange and 64 128 on another is a 0.2% spread.
The number a scanner shows is the top of book on both sides: the price of the first available lot. Your actual entry is the average price across every level you consume, so a spread is only worth what the depth underneath it allows.
A spread is also not profit. Round-trip taker fees on two venues, slippage on both legs and any funding paid while the position is open all come out of it first. The working threshold most traders settle on is well above the fee sum, not just past it.