Price impact: the cost you create
An automated market maker prices along a curve. Buying moves you up that curve, so the last unit of a large order costs more than the first. Price impact is the gap between the pool price before your trade and the average price you actually get.
It is a function of your size against the pool depth, and it is fully knowable before you sign. A 3% price impact means you are paying 3% more than the market rate because the pool is not deep enough for your order.
Slippage: the cost others create
Between your quote and your transaction landing in a block, other trades execute against the same pool. The reserves move, so your output differs from the quote. That drift is slippage, and it can go in your favour as often as against you on a calm pair.
You cannot know it in advance. You can only bound it, which is what slippage tolerance does.
Why the distinction decides what to do
High price impact is solved by trading less, splitting across time, or choosing a network where the pair has deeper liquidity. No tolerance setting touches it.
High slippage is solved by faster inclusion, a quieter moment, or a private transaction path. No trade-size change touches it.
Reading both numbers before you sign
FBT Swap shows the quoted rate, the price impact and the 0.70% platform fee in the same panel. If price impact is large, the interface says so rather than burying it — a swap that quietly costs 8% because the pool is thin is the single most common avoidable loss for a retail trader.
A useful habit: if price impact exceeds roughly 1%, check whether the same pair is deeper on another supported network before continuing.