What do the minor differences in ICs mean?

I realize this is a broad question but every time I want to buy a certain type of chip, and look on the manufacturer's website, I see several options that look the same, but have minor additions to the name. The MAX485 http://www.maximintegrated.com/datasheet/index.mvp/id/1111/t/or/pg/2#f is a good example. It comes with 18 different versions: MAX485EPA+ , MAX485ESA+T etc. etc.

Sometimes the package is different, but sometimes it is not. I just want to know if there is any easy way to tell what the difference is-not just for the MAX485 but for all of the components I buy. My main concern is that I order a chip, wait a week and then find out that there was some minor thing that made it unusable. I've looked over data sheets, and they don't usually help. For instance the datasheet lists 6 different model numbers and barely addresses the EPA+ or +T type add ons (I think just in terms of temp compatibility. Any advice on someone who knows how to easily tell whether a part will work or not? Thanks

It is sometimes not easy but the data sheet is the only place to find out however difficult. Most of the time it is just package size and meterial, like plastic or ceramic packeges, or temprature ratings. Sometimes it is die revisions or things like lead free packages. Other times there is a bit of functionality often accompanying the die revision.

Thanks

Hi, sometimes it can mean that they are only available in volume ready mounted on storage strips for auto-placement machines, or SMT strips. The different temp ratings cover milspec and tolerances for various solder processes.

Tom.... :)

Also some chips are provided by several manufacturers so that the part number also contains the manufacturer's prefix (I'm thinking of voltage regulators and 7400 logic series mainly here). In principle this can be a minor difference as the same chip design is licenced to several manufacturers who just change the logo on the die I suspect!