Anything that can hold an electric charge can be hazardous if the positive and negative terminals aren't protected against shorting. Secondly, if damaged in any way (usually a dent for the typical...
A 'hazardous chemical' is any chemical that is capable of creating a hazard by virtue of its chemical or physical properties or through interaction with another chemical or environmental condition....
basically, the difference is whatever the regulator of choice decides it is. it's fairly arbitrary. it may be based on corrosivity, or the presence of various contaminants like chromium or cyanide...