Algorithmic trading is about building an algo that determines how a market or stock will move based on news, economy, other factors.

In flash boys the front-running that these quant funds are running isn't about an algorithm, but literally all about having high capacity pipes that can see an order come in and then fill it between different exchanges and based on the minute differences in stock prices pocket the difference.

So an algo fund can lose money if the algorithm is incorrect. While front-running you never lose money.

It's basically like being a tax collector.