Hash power is a subset of computing power, so hash power is more about speed of hash function (but pretty useless for anything else), and computing power is more general processing power.  Miners secure the network by building on top of it. So every next block makes previous blocks (and thus your coins) more secure. Hash power is more like a picking algorithm on who will 'stamp' the next block, so nothing really special about it. Not sure why people are so crazy about hash power. Assume 51% (or 99%) attacker decides to make a transaction that is not valid. He processes it, and all other miners won't accept it. If that attacker proceeds with the mining, then you'll have a fork and 2 separate coins. Your normal transactions will be processed by both miners (or by only legit miners), so for you as a user it won't really matter. It can affect some honest users that sell goods for it or shitcoin traders. So for example if you buy BSV on some shady markets, you might buy attackers fakecoins, but 99.99% of people won't even know that it happened. I'm not saying 51% completely irrelevant, but it won't do much harm to the network if it happens.