1) Feeds - Send me all the data and send it fast.
Feeds are for enterprise use cases where data timeliness and availability are key requirements. Feeds allow you to backfill if your system crashes and you want to replay data. Some feeds can be configured for specific airlines or airports.
2) Alerts - Immediately send me a notification only if something interesting happens.
Alerts allow you to tightly specify what you are interested in. Our system will only push you a notification when something interesting happens (example: I only want to be notified if my flight is cancelled, otherwise I do not want any updates). We offer flight status alerts for single flight segments and trip alerts for all the out and back flight segments in your trip.
3) APIs - I want to pull on-demand data and I want to see everything available.
APIs allow you to look up all the available details when you need them. At various times, some of the returned data elements may be unavailable or unchanged from the last time you checked. The APIs are mix and match and you can poll them at different rates (example: you may only want to check airport weather every few hours but you want to check every 15 minutes to see if your flight is on-time).