I really wish people would stop calling FPGA's ASICs. Baikal (so far) has only made FPGA mining rigs. ...
How can you tell the difference?
You probably can't without physically inspecting the chips used.
This is true, and besides that, the fact that Baikals can theoretically be flashed to hash other algorithms gives it away. The Baikal miners being FPGAs also meant that they were less efficient than the D3 X11 ASICS when the D3s first came out. FPGAs are typically weaker than ASICs.
As far as I know the Giant series have never actually been "upgraded" to support additional algorithms, is that right? I realize Baikal advertises the X10 as having that ability, but that's the only hint I've seen that they may be FPGAs. Seems to me like they're ASICs unless proven otherwise by an update from Baikal or possibly a decapping inspection by someone with the knowledge and equipment to do so.
They never upgrade. If the upgrade exists it will not be upgraded until it becomes less or not profitable to use it themselves.