The difference is the reliability of the infrastructure. The single-node may become unavailable at times. it is also less powerful.
- Your project is only composed of one machine that can become unavailable when automatic updates are performed
- You have less computing power
- You can try the Squarescale service at a lower pricey
- Your project is composed of 3 or more machines. When one machine is updates, the other machines are still up to continue serving your services. Single instance services are migrated to keep running.
- You have the higher computing power for your production application
- You get the benefit on a fully reliable infrastructure by Squarescale