Might be useful to know what BJT and FET means and then you will see that standard / original TTL is always "bipolar", for example.
They are even manufactured using very different technology.
Like I said, just because it shares the same part number and is labelled "bipolar NAND gate" does not mean that it's approximately the same.
Might be useful to know what BJT and FET means and then you will see that standard / original TTL is always "bipolar", for example.