What is the main difference between standby and portable generators?

The main difference is that standby generators are permanently installed outside and automatically activate during an outage via a transfer switch, while portable generators must be manually started and rolled out when needed. Standby generators typically power the whole home or priority circuits, are quieter and more reliable, but cost more upfront. Portable generators are less expensive, flexible, and can be stored when not in use, but require manual setup and management.