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...
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...
Depends. Because alkaline batteries do not exhibit the characteristics to be classified as a reactive or ignitable waste; and because the batteries pass the Toxicity Characteristic Leaching Procedure...