and what is the difference between the longest and the real one? ask someone else. anyone can do that) no time
its world's biggest bounty if can be hacked
miners are competing. they can build on blocks they have mined but doesn't mean other miners will auto accept additional blocks. all blocks have to be valid and meet the consensus rules but longest/heaviest chain wins
https://bitcoin.stackexchange.com/questions/5540/what-does-the-term-longest-chain-mean
Discussion
Longest is the real one