Where liquidity rests
Equal highs, equal lows, previous day highs and lows, and the edges of a range are where traders place stops and breakout orders. Above highs this is buy-side liquidity; below lows it is sell-side liquidity.
Grab and sweep
A grab is fast: a single wick through the level and a close back inside. A sweep takes longer: price trades beyond the level for several candles, collects orders, then reverses. Both take liquidity; the difference is how much time price spends on the other side.
If price closes beyond the level and holds, it was not a grab at all. It was a break, and the structure lessons apply.