These new FLEX structures have a lot of unique distinguishing factors separating them from the standard Upwell product lines:

They deploy extremely quickly, with the first FLEX structures requiring just 3% of the time of previous Upwell products to deploy and activate
They can be deployed closer to other Upwell structures, with the first batch sporting minimum ranges of 150km and 200km to the nearest standard Upwell structure
They are much faster to destroy, with a single short reinforcement cycle when in full-power mode and no reinforcement cycle when in low-power mode
They come with built-in service modules that control their core function, but do not have any other slots for fitting or rigs
They do not have standard docking facilities, instead being able to be boarded directly from space like a ship so that a pilot can control their service modules
Any pilot can place fuel into FLEX structures through the Upwell Cargo Deposit system
The initial group of Upwell FLEX structures do not have any weapons, asset safety, or tethering