Difference between TTL Signetics 74S200 and 74S201 ?

[ygg-it]

74S200 and 74S201 Which is the difference?

From the datasheet there is no sign of differentiation

Both are RAM 256*1 = 256 bit Tri-state

They look not only equivalent, but also identical !

http://bitsavers.org/pdf/signetics/_dataBooks/1975_Signetics_Bipolar_Memories.pdf

In this case I'm then asking why Signetics produced the same device with different but sequential number.

Texas instruments made 74S201 only I suppose

74S200 is still on the market (ebay)

Thank you for any clarification
Kind regards