Difference between different flash chips?

[MRFICHE]

I thought I had a handle on what the difference was between the various memory chips out there, till I tried to explain it to someone else. Then I realized I didn't have a full grasp.

What is the main difference between the 27, 28, 29, and 49 - series chips? I always thought that 27 was EPROM technology, either OTP or UV-erasable, till I saw a 27F256. I thought that 28 and 29 was only Flash technology, till I saw an AT29C040-based device that can reprogram the chip in-circuit

So, can someone be kind and lay it all out?
What differentiates C from F?
What differentiates 27, 28, 29, and 49?
TIA
Brian

[Rainbow]

I even have a Winbond W27C257 - it can be electrically erased too... Until you see the datasheet, you can't be sure.