The difference between Huawei's optical module SFP and eSFP

eSFP-FE-LX-SM1310 Optical Module-eSFP-100M/155M-Single Mode Module (1310nm, 15km, LC)

SFP-GE-LX-SM1310 Optical Module-eSFP-GE-Single Mode Module (1310nm, 10km, LC)

I would like to ask what is the difference between Huawei's optical module SFP and eSFP?

In addition, in the single-mode transmission 10 km Gigabit optical module, there are:

SFP-GE-LX-SM1310 Optical Module-eSFP-GE-Single Mode Module (1310nm, 10km, LC)

In the single-mode transmission 40 km Gigabit optical module:

S-SFP-GE-LH40-SM1310 Optical Module-eSFP-GE-Single Mode Module (1310nm, 40km, LC)

So why do you want to produce a 100M optical module?

eSFP-FE-LX-SM1310 optical module-eSFP-100M/155M-single-mode module (1310nm, 15km, LC) and the transmission distance is only 15 kilometers, so I think it is not only a problem of gigabit and 100M.

Hope the expert will answer, thanks.