Differences between api.particle.io and spark-server? (Photon-OTA bug)

Does that api.particle.io server use some kind of a different software than spark-server ( or spark-protocol )?

Question is originating from OTA updates not working when doing them through the local cloud, but the exact same updates work when using the api.particle.io cloud. OTA is critical to our workflow and without it we are at a great loss. There have been promises to fix it ‘soon’ but no real hints about possible fixes have been made ( issues about this have been opened in spark-server repository).