I've read a lot about auto-scaling, that it improves performance and provides better reliability. I'm wondering what is the difference between auto scaling and load balancing? I think which of these two is better?

Why are you considering auto-scaling? Because auto scaling groups work in tandem with load balancers to keep the system healthy. I use lifeincloud.com/products/cloud-servers/ for my site. There are both auto-scaling and load balancers here, you should consider both options, because they are inseparable. They are essential tools for managing large systems and improve the performance of cloud and network infrastructure.