I always thought that the 1N4148 was an improved replacement for the obsolete 1N914, but I see that the 1N914 is still produced, and overmore, looking at the parameters for both on digikey they seem to be identical. What was the reason to create the 1N4148 if it's identical to the existing 1N914?
Since leakage is usually an undesirable property, today manufacturers produce the 1N4148 and sell it as either part number.
There are 1N914, 1N914A, 1N914B, 1N916, 1N916A, 1N916B, 1N4148, 1N4448, with fairly subtle differences between them.
Looking at the Fairchild datasheet, the guaranteed max capacitance is less for the 916A/B and 4448 than the 914A/B/4184 (2pF vs. 4pF), and the forward voltage min/max ratings differ, but there's nothing I see that prevents them all from being made with a single die.
In particular, there is no difference at all between part numbers on any of the 'typical' curves.