--among what most doctors consider "acute", "sub-acute", and "chronic" onset, but dahlek beat me to it.

The borders between then are a bit arbitrary, but yes, the major differences are how long does it take to go from no symptoms to major symptoms. In a chronic case, the progression in insidious in that one first starts noticing little things that gradually increase in severity and intensity over months/years; with the other categories the time from "nothing" to full-blown symptoms is much shorter.

And yes, chronic inflammatory demeylinating polyneuropathy (CIDP), has been considered the sub-acute, lingering form of Guillain Barre syndrome by many researchers (though there's some dispute about this). There are some similarities--autoimmune demyelinating attack, infectious prodrome, etc., and, in many people, a relapsing/remitting (flares) characteristic that is somewhat common in autoimmune disorders.

It's very hard to analyze these things at the time they'e going on--one is generally much more worried and concerned about the situation that is ongoing--it's only in retrospect that most can generalize about the timing and appearance of symptoms. It's why many people keep a diary or other written record of how they feel, so they can note the differences day to day, week to week, month to month.