There are a ton of technology differences which the upcoming Filecoin v2 paper will address (very soon!).
On the conceptual layer there's a difference in that Sia and Storj seem to be a bit more geared towards consumers and file storage, while IPFS+Filecoin's aim is to be infrastructure in the commons.
On the conceptual layer there's a difference in that Sia and Storj seem to be a bit more geared towards consumers and file storage, while IPFS+Filecoin's aim is to be infrastructure in the commons.
(Disclosure: IPFS & libp2p dev)