On Bitcoin-Wiki's page about Blocks, it says that "Bitcoin transactions are broadcast to the network by the sender, and all peers trying to solve blocks collect the transaction records and add them to the block they're working to solve.".
So, do all peers have the same transactions in their blocks at all times?
Miners will naturally be inclined to include those transactions in their blocks that give them high transaction fees (though exceptions exist), because apart from the block reward from coinbase transaction, those are the only incentives for miners. So, whatever transactions have reached a miner through the network, her choices will be restricted among those transactions. At a particular time instance, different miners most likely have different snapshots of transactions available to them. So, the answer is no (with very very high probability).
All valid unconfirmed transactions are broadcasted on the Bitcoin network, therefore all miners in principal have access to the same transactions.
However, the individual miners may receive knowledge of transactions in different order, select transactions to include in blocks by different rules, or may not yet have received every transaction that is currently unconfirmed.
Therefore, each miner has an individual subset of the same set of unconfirmed transactions.
Well long answer is No because transactions take time to relay between all peers. If you send coins from a multibit wallet you can see how many peers have seen the transaction, however it takes some time to relay it to all the peers.
Once a block is found, then ALL the peers get a notification that a new block was found and they add it to their respective chains. That is how all the peers stay synchronized on the same chain.
Hope I answered your question!
