Nextel Oem

What is the difference between NNTN4655, SNN5706, SNN5742 and SNN5615 Motorola OEM Cellphone Batteries?
Our Nextel 158sr phones here at work have NNTN4655 batteries in them. I went looking for some replacements, and have seen all sorts of batteries purporting to be ‘replacements’ for the NNTN4655. I wouldn’t mind a different stock number, but from what I can tell, these other stock numbers have less talk or standby time, even though they are the ‘fat’ or ‘extended life’ batteries, too.
I like a bargain as much as anyone, but the owners want OEM, so that means Motorola, and they want — and I do, too — to have at least as much talk and standby time (using the walkie-talkie feature more than the cellphone feature) as they are used to having with the NNTN4655.
This is a technical question and i will advice to look in the User Manual for the correct battery type or see that moto has changed it code or replaced the battery type in market for this type. $
BlackBerry Curve 8350i OEM Housing – NEXTEL