They race against each other to produce a hash for a next block. The first pool or solo miner to produce a hash that exceeds the current "difficulty" get recognised as the "next block".
So, yes, they mine the "next block" simultaneously all the time, but the transactions inside that block is not necessarily the same.
Topic: Can different pools mine the same block at the same time? (Read 818 times)
Can 2-3 or more pools mine the same block simultaneously. If so, who'll get the block?
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