They are quite different: MEGA is a web-based file hosting, spideroak is a desktop app that syncs your local files to the cloud for sync&backup. Spideroak is f

They are quite different: MEGA is a web-based file hosting, spideroak is a desktop app that syncs your local files to the cloud for sync&backup. Spideroak is for your own private storage (+ShareRoom for sharing with a group), MEGA is positioning primarily for filesharing. Yes, they both use encryption for files without sharing the key with the service provider but that's as far as I'd go with the similarity.